Create RatMaze.java

this is the solution to the rat in a maze problem form geeksforgeeks

Author: ayushs1ngh

Practice Problems/Backtracking/Rat In A Maze/RatMaze.java

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+/* Java program to solve Rat in a Maze problem using backtracking */
+
+public class RatMaze { 
+
+	// Size of the maze 
+	static int N; 
+
+	/* A utility function to print solution matrix sol[N][N] */
+	void printSolution(int sol[][]) 
+	{ 
+		for (int i = 0; i < N; i++) { 
+			for (int j = 0; j < N; j++) 
+				System.out.print( 
+					" " + sol[i][j] + " "); 
+			System.out.println(); 
+		} 
+	} 
+
+	/* A utility function to check if x, y is valid index for N*N maze */
+	boolean isSafe( 
+		int maze[][], int x, int y) 
+	{ 
+		// if (x, y outside maze) return false 
+		return (x >= 0 && x < N && y >= 0
+				&& y < N && maze[x][y] == 1); 
+	} 
+
+	/* This function solves the Maze problem using 	Backtracking. It mainly uses solveMazeUtil() to solve the problem. It returns false if no path is possible, otherwise return true and 
+	prints the path in the form of 1s. Please note that there may be more than one solutions, this function prints one of the feasible solutions.*/
+	boolean solveMaze(int maze[][]) 
+	{ 
+		int sol[][] = new int[N][N]; 
+
+		if (solveMazeUtil(maze, 0, 0, sol) == false) { 
+			System.out.print("Solution doesn't exist"); 
+			return false; 
+		} 
+
+		printSolution(sol); 
+		return true; 
+	} 
+
+	/* A recursive utility function to solve Maze problem */
+	boolean solveMazeUtil(int maze[][], int x, int y, 
+						int sol[][]) 
+	{ 
+		// if (x, y is goal) return true 
+		if (x == N - 1 && y == N - 1
+			&& maze[x][y] == 1) { 
+			sol[x][y] = 1; 
+			return true; 
+		} 
+
+		// Check if maze[x][y] is valid 
+		if (isSafe(maze, x, y) == true) { 
+			// mark x, y as part of solution path 
+			sol[x][y] = 1; 
+
+			/* Move forward in x direction */
+			if (solveMazeUtil(maze, x + 1, y, sol)) 
+				return true; 
+
+			/* If moving in x direction doesn't give solution then Move down in y direction */
+			if (solveMazeUtil(maze, x, y + 1, sol)) 
+				return true; 
+
+			/* If none of the above movements works then BACKTRACK: unmark x, y as part of solution path */
+			sol[x][y] = 0; 
+			return false; 
+		} 
+
+		return false; 
+	} 
+
+	public static void main(String args[]) 
+	{ 
+		RatMaze rat = new RatMaze(); 
+		int maze[][] = { { 1, 0, 0, 0 }, 
+					           { 1, 1, 0, 1 }, 
+						         { 0, 1, 0, 0 }, 
+					           { 1, 1, 1, 1 } }; 
+
+		N = maze.length; 
+		rat.solveMaze(maze); 
+	} 
+}