Java Maze Solver Using Stacks

The left top cell is the entry point and right bottom cell is the exit point. Evaluation of an infix expression that is fully parenthesized using stack in java. When I found your problem, I actually laughed out loud. C 2 years software development using Agile methodologies D 2 years Full-stack development experience. Thanks for contributing an answer to Robotics Stack Exchange! Please be sure to answer the question. Since the "best" solution is a tall order for an 8-bit microcontroller, focus on a "dumb" solution that actually works: use whisker sensors and the right-hand rule. is it possible that I can insert a multidimensional array in a stack,how?:S (can you please give me some little bit of codes in order to do that) I did already a maze using a recursion,but the requirements have been changed by my profit should have no. In this method, the breadth first search (BFS) is used to traverse. The code is open for use and modification with due credit given. DFS can be implemented in two ways. The algorithm does not use a clever stragtegy to solve the puzzle. Dijkstra implementation for maze solving that works fine and returns shortest path. If you use wall following with the right hand, you should place your hand on the right wall. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. Skills: Java See more: maze solving algorithm shortest path, fastest maze solving algorithm, depth first search maze solver java, breadth first search maze solving, maze solving algorithm java, maze solving algorithm python, maze solving algorithm c++, maze solving algorithm in c, open pdf file using desktop application. The Overall Pseudocode Of The Algorithm Is The Following. Firstly, we will make a matrix to represent the maze, and the elements of the matrix will be either 0 or 1. One maze I am trying to solve looks like this. A good heuristic should expand 1600 nodes or less. Clearly, this code requires a recursion stack, hence the space complexity is equal to the depth of the stack. The starting cell is at the bottom left (x=0 and y=0) colored in green. The output is the series of coordinates (row, column) of the path to the destination. Unit blocks (representing 1s) and X-boxes (for the unknown, X), are placed on the pans of a balance beam. Implement a Breadth First Search in C++ as a maze solver, the entire code is written and functional except for the algorithm for the findMaze(position **predecessor) function. The Approach. Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Created Nov 5, 2015. Convert your '*'s and '. The code is open for use and modification with due credit given. The input is an array of 1s and 0s and the row and column of the destination. In the new stack the two 9s would be the first values popped from the stack. What algorithm have you used in the past to generate a simple 2d maze? Stack Exchange Network Stack Exchange network consists of 175 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Stack is an area of memory that holds all local variables and parameters used by any function and remembers the order in which functions are called so that function returns occur correctly. java This textbook presents material using the Java programming language. Next, we visit the element at the top of stack i. I just completed a program that uses recursion to get through a maze specified by a two-dimensional 12x12 array. One of the requirements is to be able to back track when reaching a dead end. * * @author Java Foundations * @version 4. Using the same with euclidean distance expands even 103081 nodes. Making statements based on opinion; back them up with references or personal experience. 3 Linked Structures of Introduction to Computer Science by Robert Sedgewick and Kevin Wayne. public class Maze { private Cell cellArray [ ] ; // An array to store all the cells of the maze. If Step is the end cell: Push Step onto the. Hi, I'm having trouble with my current program here. Blockly Games: Maze 1 10 Stack a couple of 'move forward' blocks together to help me reach the goal. A copy should be on reserve in the library. Java offers many benefits, and programmers often view Java as a safer, more portable, and easier-to-use language than C++. The code should print a path of 'x's from start([1][1]) to end([8][13]) by checking for an empty. Help with a maze solver I have an assignment that is to use the right hand method to solve a maze. Join over 5 million developers in solving code challenges on HackerRank, one of the best ways to prepare for programming interviews. The developer can use Red-Black Tree in the following use cases. Write a C Program to convert prefix to postfix using stack. A Maze is given as N*M binary matrix of blocks and there is a rat initially at (0, 0) ie. You’ll need sufficient memory to store the entire maze in memory, though, and it requires stack space again proportional to the size of the maze, so for exceptionally large mazes it can be fairly. The algorithm does not use a clever stragtegy to solve the puzzle. If filename does not meet the. Please import it by right-clicking in your package explorer, choosing import->general->archive file. Use | for vertical wall, -for horizontal wall and + for corner. How can I access Java's built-in Stack / Queue instead of the introcs one?. /** * Lays out the frame and buttons for the maze solver. You know about the problem, so let's see how we are going to solve it. Logic mazes appeared in June 2009, at the World Science Festival Street Fair in Manhattan, in January 2010, at Mathematics Games Day at a school in Hong Kong, and in May 2010, at FESTIMATE in Lima, Peru. It provides a a random maze generator game, which can generate mazes of any dimension and solve it. This element is set when the point is enqueued. Walk-through logic mazes first appeared on farms, but they are now spreading to cities. A Maze is given as N*N binary matrix of blocks where source block is the upper left most block i. The purpose of this lab is to: Have you implement a Stack and a Queue, Build a simple linked list of nodes, Use your stack and queue to solve a maze,. Both methods are easier to carry out when the variable argument list is at the end, which isn't the case here: the final argument to mv is the destination. Works with gridworld : Dice Flip-- Cay Horstmann: CS1-CS2, prolog for advanced CS2, java for late CS1 variant. You may use a single queue as auxiliary storage to solve this problem. This problem illustrates searching using stacks (depth-first search) and queues (breadth-first search). Using another array of Point corresponding to each element in the maze, allow each element to point to its "predecessor" in the breadth-first tree. com Armon Saied [email protected] No need for maintaining a Stack, since you are not using any of Stack's method but only add, which you can also use with a List. The methods should paint the animations for the create and solve processes on the mazePanel in the MazeWindow. txt file with C and C++ for Java Programmers - November 5, 2011;. An ArrayList is the appropriate structure to use here, since we can start off with an empty ArrayList and use the add() and remove() methods as needed to add cells to the end of the path or remove them. Learning how to count money is only one of the many math games found at Apples4theteacher. 3 Stacks and Queues. It has to be a direct computation. The most common example is commented-out code that contains comments itself, and the fix is to remove the code instead of commenting it out. Very simple depth first search and breath first graph traversal. Solving a maze 17 posts Hi, I'm playing around with maze solving in Java. Using Stacks: Algorithms for Infix, Postfix, and Prefix i. Similar applications use graphs in such situations but this article shows how this can be done without the headache of graphs. I show an. Q&A for scientists using computers to solve scientific problems. Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. An algorithm for returning the node at the. On the other hand, using a queue results in a breadth-first search of the maze, where the oldest potential trail is always expanded next. maze[0][0] and the rat wants to eat food which is present at some given block in the maze (fx, fy). Write a C program to implement stack data structure using linked list with push and pop operation. NET The Algorithm Push starting Location onto stack. Web browsers do use stack data structure. #include #include #include "maze. The input * method load supports a data format used to store * a maze in a text file. This object creates a maze based on a users inputs, it can print, redesign and track a route and find if it can be solved. Can be easily adapted for use with GridWorld API; and a more complex version implementing A* is appropriate for an intro AI course. The article presents a simple technique to find the shortest path between two points in a 2D Maze. While the stack isn’t empty and we aren’t at the end: Pop stack to get current location. You can use whatever structure you find meaningful; in our case, we let ‘P’ represent the current path. I'm writing a program to solve a maze. Infix notation is the common arithmetic and logical formula notation, in which operators are written infix-style between the operands they act on (e. You will use a stack to solve a maze. java, That Uses Stacks And Queues To Implement An Algorithm To Escape From A Maze. maze-generator maze-solver java Updated Jul 11, 2017. java * Execution: java EvaluatePostfix < file. Thanks for contributing an answer to Robotics Stack Exchange! Please be sure to answer the question. In this Java tutorial we will see Why java. The main part of your assignment is to write a program called Solve. First video in a (possibly) short series where we write a maze solving program in Java. Two white pixels are. What i have done:- read the maze from a txt file- display it on a JPanel object- created an enum (look below)- class MyStack and MyQueue- Implements agenda which specifies 5 methods public enum Square { start(o), openSpace(. java use recursion and stack to solve. We are supposed to find a path out of a maze using a coordinate class. com Please email me at the address above if you have questions or comments. Given a maze with obstacles, count number of paths to reach rightmost-bottommost cell from topmost-leftmost cell. We designate the nested class as private because clients do not need to know any of the details of the linked lists. java Note: Maze. java from §4. One way to use it would be multistart. The class is based on the basic principle of last-in-first-out. Declaration. It extends class Vector with five operations that allow a vector to be treated as a stack. Java offers many benefits, and programmers often view Java as a safer, more portable, and easier-to-use language than C++. The maze always starts at and ends at. A TDD approach to implement a simple maze by well known algorithms in Java. For the pledge algorithm your source says. June 13, 2019 2:40 PM. Once complete, the robot can simply walk through the maze in one try. The article presents a simple technique to find the shortest path between two points in a 2D Maze. Implement DevOps principles to take full advantage of the AWS stack and services; Take expert look at solving problems faced by real developers and operation teams and learn to overcome them. Java allows us to define and use other classes within class implementations in this natural way. /***** * Compilation: javac EvaluatePostfix. Find the shortest path, if possible, from entry to exit through non blocked cells. Are stacks and queues useful? • YES. I'm writing a mouse than can solve a 2D maze, 16*16 cells. Below is the class of the functionality of the test, package Pages; import java Stack Exchange Network Stack Exchange network consists of 175 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. java Note: Maze. The book starts with an introduction covering the essentials, but assumes you are just refreshing, are a very fast learner, or are an expert in building web services. Following example shows how to implement stack by creating user defined push() method for entering elements and pop() method for retrieving elements from the stack. /* Finding the solution out of a maze. Walk-through logic mazes first appeared on farms, but they are now spreading to cities. DFS can be implemented in two ways. Java Maze Solver. Description. 1 Analysis of Micromouse Maze Solving Algorithms David M. CSCI 151 - Stacks and Queues Simply A-Maze-ing! Due 10:00pm, Sunday, Feb. java is a Java Console application which creates a simple undirected graph and then invokes the DFS and BFS traversal of the graph. I just completed a program that uses recursion to get through a maze specified by a two-dimensional 12x12 array. You could also improve your current algorithm a little bit. Java Maze Solver. We are supposed to find a path out of a maze using a coordinate class. Solving a Maze using stacks. * * @author Java Foundations * @version 4. An object representing a position in the maze is pushed onto the stack when trying a path. In this lab you will use the power of a stack and a queue to explore and find your way through a maze. While selecting the next step, we need to make sure that we don't try to go to a position that is already a part of our current solution path. 6MB memory stack use 1ms and 34. Works with gridworld : Dice Flip-- Cay Horstmann: CS1-CS2, prolog for advanced CS2, java for late CS1 variant. Data Structures and Problem Solving Using C++ (2nd Edition) by Mark Allen Weiss. I'm using a stack of type coordinate. Each cell contains an array of 4 walls which can be "knocked down" by setting an element in the array to zero. to solve text based mazes using a Stack data structure. Maze solving You are encouraged to solve this task according to the task description, using any language you may know. Frequently implemented with a stack, this approach is one of the simplest ways to generate a maze using a computer. It consists of three rods, and a number of disks of different sizes which can slide onto any rod. Your source file is in the form of an exported eclipse project. The starting point is a rectangular grid whose dimensions range from 2 to 50. java to read in the. - For unlimited recursion use 0. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack, a method to test for whether the stack is empty, and a method to search the stack for an item and discover how far it is from. Use a Stack to Solve a Maze. Q: Is the recursive version usually faster? A: No -- it's usually slower (due to the overhead of maintaining the stack) Q: Does the recursive version usually use less. Tracing backward from point to point gives the actual path. As you can see from the UML design, the Maze class generates the maze and contains a collections of Cells to work the algorithm. A maze created from a 2D array can be solved using recursion similar to like we did for the previous. Convert your '*'s and '. currentTimeMillis()method of Date class. edu We would like to develop a real-time maze-solving app for the Android mobile platform. And example from Oracle:. * * % more tobe. This tutorial covers about what is Towers of Hanoi puzzle and how to solve the puzzle using recursion. The app would be able to analyze an image of a general maze and use image processing algorithms to binarize the image into a black-white rep-. One of the problems of artificial intelligence is to solve tortuous games (MAZE). Play around with algorithms to solve a maze. Submitted by Abhishek Jain, on June 19, 2017 As discussed in Infix To Postfix Conversion Using Stack, the compiler finds it convenient to evaluate an expression in its postfix form. This program loads a maze from a local text file and then checks if there is a path from position 0,0 to the bottom-right most position. Maze solver using. import java. If you are freely importing everything from that package, make sure you're not accidentally using the wrong Timer! The maze itself From the previous homework, you have a Maze class that stores char or Square and can read from a Scanner. maze file, and call getVertices() to retrieve the graph. If you're going to use a single machine for it you'll need to launch both master and slave on it. I use a class Point that contains 2 ints which are used for subscripting the vector of. Below is the syntax highlighted version of EvaluatePostfix. The whole principle behind this algorithm is that you can solve any continuous, i. Using another array of Point corresponding to each element in the maze, allow each element to point to its "predecessor" in the breadth-first tree. * A private representation whether we've tried to solve a maze, and * succeeded. Making statements based on opinion; back them up with references or personal experience. Interactive money game - count pennies, nickels, dimes and quarters to total the amount given. This was my grade 12 final computer science project written in Java using the growing tree algorithm, Java swing libraries, OOP, inheritance, and more. If you are freely importing everything from that package, make sure you’re not accidentally using the wrong Timer! The maze itself From the previous homework, you have a Maze class that stores char or Square and can read from a Scanner. This was my grade 12 final computer science project written in Java using the growing tree algorithm, Java swing libraries, OOP, inheritance, and more. A maze created from a 2D array can be solved using recursion similar to like we did for the previous. The starting point is a rectangular grid whose dimensions range from 2 to 50. *; import java. no "islands", maze by following either the right hand or left hand wall. java, That Uses Stacks And Queues To Implement An Algorithm To Escape From A Maze. Lab 5: The Maze Lab Due: March 26th at 11:59pm Overview The goal of this lab is to implement Stack and generate a solve a maze using a depth-first-search routine, as well as implement a Queue to solve a maze using breadth-first search. you can also use "one hand touches wall". The matrix defines the maze, the stack keeps track of decision points, and the list records the solution. They come up all the time. Depth-first search (DFS) for undirected graphs Depth-first search, or DFS, is a way to traverse the graph. 6MB memory stack use 1ms and 34. If you wish to do backtracking after you find the shortest path from your start node to the goal node, you can decide to simply put the all found nodes into a stack as you find them and in the end simply pop all nodes from the stack to see the path. Maze Solving. I'm writing a mouse than can solve a 2D maze, 16*16 cells. The algorithm requires around 256 X 3 bytes of menory. * Class to construct a random, simple, and, a perfect maze and then solve the maze using Breadth-First Search (BFS) & Deep-First Search (DFS). Algebra Balance Scales. We designate the nested class as private because clients do not need to know any of the details of the linked lists. This way you don't have to loop through the entire array. Given a maze, NxN matrix. A maze created from a 2D array can be solved using recursion similar to like we did for the previous. After extracting the files, make sure to update your CLASSPATH to include the directory in which this code was extracted. The output is the series of coordinates (row, column) of the path to the destination. You can use whatever structure you find meaningful; in our case, we let ‘P’ represent the current path. Recursive part(s) that call the same algorithm (i. The program works pretty much the way I wanted it to, but I was wondering if there was a way to stop the collapsing of functions once a return; line is reached other than by using a loop for most of the lines in the function. we have been given only the code to input the maze in character arrays. It is a powerful tool for solving segmentation problems in densely packed objects and other difficult images, such as an image of biological tissue or a container full of objects. The whole principle behind this algorithm is that you can solve any continuous, i. I am using keyword driven framework to create the script in selenium. com Please email me at the address above if you have questions or comments. Maze Generation - Master's Thesis (Java Applet enabling users to have a maze created using various algorithms and human solving of mazes) Maze generator and solver, in C# - print out mazes in various shapes on paper. This 2D array will store the current partial solution path. I am having problems backtracking in my while loop. In this lesson we will be creating a C# form that creates and solves a maze using a recursive technique. The Overall Pseudocode Of The Algorithm Is The Following. I had to make both types of maze traversal programs using java, I found the recursion form was much easier, now im trying to do the maze traversal using stacks, ive tried modifying my switch states, tried modifying my location class to contain a variable to tell how many times that location has been checked and I just cannot get it to work properly, it either goes around in a circle and fills. How to handle the empty stack exception ? Solution. Join GitHub today. After doing a thorough search, I have only come up with one possibility. Write a C Program to convert prefix to postfix using stack. Btw, If you are preparing for programming job interviews and looking for some coding problems to prepare well, then I will recommend you to go through problems given in the book, Cracking the Coding Interview. If you're going to use a single machine for it you'll need to launch both master and slave on it. First video in a (possibly) short series where we write a maze solving program in Java. If we use a stack, we search the maze in a depth-first manner: we explore down a trail as far as possible, and backtrack only if we reach a dead end, because we always search the youngest potential trail next. This was my grade 12 final computer science project written in Java using the growing tree algorithm, Java swing libraries, OOP, inheritance, and more. The output is the series of coordinates (row, column) of the path to the destination. In this method, the breadth first search (BFS) is used to traverse. A good heuristic should expand 1600 nodes or less. The walls are colored in blue. We have to create coordinates and then push them onto a stack. At the end we have to pop the stack to get the path coordinates. import java. Split the stack of cards into two halves of about the same size. */ private Stack< MazePosition > solution; /** * Creates a maze solver that is set up to use the maze designated in * filename. By continuing to use Pastebin, you agree to our use of cookies as described in the Cookies Policy. Java is a language that is often examined in comparison with C++. In this article, we'll explore possible ways to navigate a maze, using Java. Course Overview and Goals The CodeHS AP Java course is a year-long course designed to help students master the basics of Java and equip them to successfully pass the College Board AP Computer Science A Exam at the end of the school year. NET The Algorithm Push starting Location onto stack. Though we can minimize and avoid java. It extends class Vector with five operations that allow a vector to be treated as a stack. If you are freely importing everything from that package, make sure you’re not accidentally using the wrong Timer! The maze itself From the previous homework, you have a Maze class that stores char or Square and can read from a Scanner. All 238 Java A generic C++ implementation of a Maze data structure along with maze solving algorithms using graphs. Please follow the link Backtracking | Set 2 (Rat in a Maze) - GeeksforGeeks Hope this will help you in understanding. We are supposed to find a path out of a maze using a coordinate class. Making statements based on opinion; back them up with references or personal experience. 3 Linked Structures of Introduction to Computer Science by Robert Sedgewick and Kevin Wayne. This post describes how to solve mazes using 2 algorithms implemented in Python: a simple recursive algorithm and the A* search algorithm. Remember that a recursive algorithm has at least 2 parts: Base case(s) that determine when to stop. This program loads a maze from a local text file and then checks if there is a path from position 0,0 to the bottom-right most position. Maze game using stack in c The following C project contains the C source code and C examples used for maze game using stack. You must rely on Maze. Stack Overflow - Java Tutorials. Firstly, we will make a matrix to represent the maze, and the elements of the matrix will be either 0 or 1. The idea is inspired from Lee algorithm and uses BFS. When I found your problem, I actually laughed out loud. Having A Lot Of Trouble On A Java Maze Program Using Stacks Maze Traversal Using Stacks JAVA; Recursive Maze Solution - Solving A Maze In Java; Solving A Maze; Maze, Using JButtons And Recursion. Please follow the link Backtracking | Set 2 (Rat in a Maze) - GeeksforGeeks Hope this will help you in understanding. Java program to solve count the path in a Maze problem using backtracking - CountPathInMaze. Star 0 // public Stack locations = new Stack> where Square is an enum that contains the kind of square (empty, wall, etc. It's been awhile since I last asked for help because I've been doing rather well with my programming thus far. The Approach. This is the actual method used in puyo puyo and other apps such as the fill-bucket tool in paint or a maze solver. public class Maze { private Cell cellArray [ ] ; // An array to store all the cells of the maze. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. Your program will take in from a file 2 things. util library, which means, you'll have to do ALL the implementation work yourself. * * % more tobe. In this lesson we will be creating a C# form that creates and solves a maze using a recursive technique. The basic steps are two-fold: Test different key lengths, and look for a length where the letters in each column look like they might plausibly be consecutive. Red–black tree is a binary search tree with an extra bit of data per node, its color, which can be either red or black. Evaluation of an infix expression that is fully parenthesized using stack in java. Consider the maze to be a black and white image, with black pixels representing walls, and white pixels representing a path. I'm writing a program to solve a maze. While selecting the next step, we need to make sure that we don't try to go to a position that is already a part of our current solution path. Download any course Open app or continue in a web browser Log in Register Step 1 of 2 2. There is a repository on GitHub to solve a maze written in Java. Maze solver --- CS2 students implement a given algorithm that uses queues or stacks to manage a search through a given maze, to find whether it's solvable or not. For example, you seem to be using your path stack both to store the final solution to the maze as well as to store parts of paths you have not fully checked (and may not be the correct solution). java is a Java Console application which creates a simple undirected graph and then invokes the DFS and BFS traversal of the graph. Here's simple Program to convert prefix expression to postfix expression using stack in C Progr/. I just completed a program that uses recursion to get through a maze specified by a two-dimensional 12x12 array. I dont know how to use stack in this maze?,the stack will be the one who will store the paths and I want the program to not use recursion,how can I do that in this program? a similar algorithm for this one is listed below,but what I did is so different from this algo Find the starting point look for the letters along the border of your maze. Help with a maze solver I have an assignment that is to use the right hand method to solve a maze. Depth-first search (DFS) for undirected graphs Depth-first search, or DFS, is a way to traverse the graph. Algorithm to solve a rat in a maze. Both solutions are optimized and compared. /** * Maze * * This class represents a rectangular maze. Also see his Maze on Mars, a wallpaper graphic image for Windows 95/NT. It is a powerful tool for solving segmentation problems in densely packed objects and other difficult images, such as an image of biological tissue or a container full of objects. • We keep doing this until we reach a problem that is simple enough to be solved directly. Implementation of different maze generation algorithms - mgaut72/Mazes. Submitted by Abhishek Jain, on June 19, 2017 As discussed in Infix To Postfix Conversion Using Stack, the compiler finds it convenient to evaluate an expression in its postfix form. setPenRadius() to draw the corridors as fat white lines on a black background. Two white pixels are. With Python support for Application Security Monitoring, Threat Stack customers who use Python with Django and Flask frameworks can ensure security in the software development lifecycle with risk. Stacks in Java. A rat starts from source and has to reach the destination. This will always get you out, unless the finish is is a "island," like the picture below. These tools run a command several times, with as many arguments as can be passed in one go. While the stack isn't empty and we aren't at the end: Pop stack to get current location. How To Perform Calculations Using Stacks Java; Infix To Postfix Using Stacks; Need Help Solving Maze Using Recursion; Recursive Maze Help. So my assignment is to solve a maze using stacks in Java. The Tower of Hanoi is a mathematical game or puzzle. We use an undirected graph with 5 vertices. There is much more than a little difference between them. 0 */ public class LinkedStack implements StackADT { private LinearNode. After doing a thorough search, I have only come up with one possibility. In this article, we'll explore possible ways to navigate a maze, using Java. java from 4. Algorithm to solve a rat in a maze. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. We'll solve the problem of finding and marking a solution path using recursion. Your source file is in the form of an exported eclipse project. You could also improve your current algorithm a little bit. To solve a maze, imagine you're in that maze. I do not believe you are using the stacks correctly. It's doing way too much. Your program will take in from a file 2 things. C Program to Evaluate POSTFIX Expression Using Stack, the program implemented with push and pop operations. Skip to content. txt * to be not that or be (2 left on stack) * *****/ import java. With Python support for Application Security Monitoring, Threat Stack customers who use Python with Django and Flask frameworks can ensure security in the software development lifecycle with risk. Tracing backward from point to point gives the actual path. If you start to enter another number, the numbers already on the stack jump up to make room for the new number. A Maze is given as N*M binary matrix of blocks and there is a rat initially at (0, 0) ie. 0 International License. 04 by the way) and using the Backup and Restore using the custom/ Stack Exchange Network Stack Exchange network consists of 175 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. An object representing a position in the maze is pushed onto the stack when trying a path. The fact-checkers, whose work is more and more important for those who prefer facts over lies, police the line between fact and falsehood on a day-to-day basis, and do a great job. Today, my small contribution is to pass along a very good overview that reflects on one of Trump’s favorite overarching falsehoods. Namely: Trump describes an America in which everything was going down the tubes under  Obama, which is why we needed Trump to make America great again. And he claims that this project has come to fruition, with America setting records for prosperity under his leadership and guidance. “Obama bad; Trump good” is pretty much his analysis in all areas and measurement of U.S. activity, especially economically. Even if this were true, it would reflect poorly on Trump’s character, but it has the added problem of being false, a big lie made up of many small ones. Personally, I don’t assume that all economic measurements directly reflect the leadership of whoever occupies the Oval Office, nor am I smart enough to figure out what causes what in the economy. But the idea that presidents get the credit or the blame for the economy during their tenure is a political fact of life. Trump, in his adorable, immodest mendacity, not only claims credit for everything good that happens in the economy, but tells people, literally and specifically, that they have to vote for him even if they hate him, because without his guidance, their 401(k) accounts “will go down the tubes.” That would be offensive even if it were true, but it is utterly false. The stock market has been on a 10-year run of steady gains that began in 2009, the year Barack Obama was inaugurated. But why would anyone care about that? It’s only an unarguable, stubborn fact. Still, speaking of facts, there are so many measurements and indicators of how the economy is doing, that those not committed to an honest investigation can find evidence for whatever they want to believe. Trump and his most committed followers want to believe that everything was terrible under Barack Obama and great under Trump. That’s baloney. Anyone who believes that believes something false. And a series of charts and graphs published Monday in the Washington Post and explained by Economics Correspondent Heather Long provides the data that tells the tale. The details are complicated. Click through to the link above and you’ll learn much. But the overview is pretty simply this: The U.S. economy had a major meltdown in the last year of the George W. Bush presidency. Again, I’m not smart enough to know how much of this was Bush’s “fault.” But he had been in office for six years when the trouble started. So, if it’s ever reasonable to hold a president accountable for the performance of the economy, the timeline is bad for Bush. GDP growth went negative. Job growth fell sharply and then went negative. Median household income shrank. The Dow Jones Industrial Average dropped by more than 5,000 points! U.S. manufacturing output plunged, as did average home values, as did average hourly wages, as did measures of consumer confidence and most other indicators of economic health. (Backup for that is contained in the Post piece I linked to above.) Barack Obama inherited that mess of falling numbers, which continued during his first year in office, 2009, as he put in place policies designed to turn it around. By 2010, Obama’s second year, pretty much all of the negative numbers had turned positive. By the time Obama was up for reelection in 2012, all of them were headed in the right direction, which is certainly among the reasons voters gave him a second term by a solid (not landslide) margin. Basically, all of those good numbers continued throughout the second Obama term. The U.S. GDP, probably the single best measure of how the economy is doing, grew by 2.9 percent in 2015, which was Obama’s seventh year in office and was the best GDP growth number since before the crash of the late Bush years. GDP growth slowed to 1.6 percent in 2016, which may have been among the indicators that supported Trump’s campaign-year argument that everything was going to hell and only he could fix it. During the first year of Trump, GDP growth grew to 2.4 percent, which is decent but not great and anyway, a reasonable person would acknowledge that — to the degree that economic performance is to the credit or blame of the president — the performance in the first year of a new president is a mixture of the old and new policies. In Trump’s second year, 2018, the GDP grew 2.9 percent, equaling Obama’s best year, and so far in 2019, the growth rate has fallen to 2.1 percent, a mediocre number and a decline for which Trump presumably accepts no responsibility and blames either Nancy Pelosi, Ilhan Omar or, if he can swing it, Barack Obama. I suppose it’s natural for a president to want to take credit for everything good that happens on his (or someday her) watch, but not the blame for anything bad. Trump is more blatant about this than most. If we judge by his bad but remarkably steady approval ratings (today, according to the average maintained by 538.com, it’s 41.9 approval/ 53.7 disapproval) the pretty-good economy is not winning him new supporters, nor is his constant exaggeration of his accomplishments costing him many old ones). I already offered it above, but the full Washington Post workup of these numbers, and commentary/explanation by economics correspondent Heather Long, are here. On a related matter, if you care about what used to be called fiscal conservatism, which is the belief that federal debt and deficit matter, here’s a New York Times analysis, based on Congressional Budget Office data, suggesting that the annual budget deficit (that’s the amount the government borrows every year reflecting that amount by which federal spending exceeds revenues) which fell steadily during the Obama years, from a peak of $1.4 trillion at the beginning of the Obama administration, to $585 billion in 2016 (Obama’s last year in office), will be back up to $960 billion this fiscal year, and back over $1 trillion in 2020. (Here’s the New York Times piece detailing those numbers.) Trump is currently floating various tax cuts for the rich and the poor that will presumably worsen those projections, if passed. As the Times piece reported: