Create Rat In A Maze

Author: akshayavb99

Course 2 - Data Structures in JAVA/Lecture 14 - Backtracking/Rat In A Maze

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+/*
+You are given a N*N maze with a rat placed at maze[0][0]. Find whether any path exist that rat can follow to reach its destination i.e. maze[N-1][N-1]. Rat can move in any direc­tion ( left, right, up and down).
+Value of every cell in the maze can either be 0 or 1. Cells with value 0 are blocked means rat can­not enter into those cells and those with value 1 are open.
+
+Input Format
+Line 1: Integer N
+Next N Lines: Each line will contain ith row elements (separated by space)
+
+Output Format :
+The output line contains true if any path exists for the rat to reach its destination otherwise print false.
+
+Sample Input 1 :
+3
+1 0 1
+1 0 1
+1 1 1
+Sample Output 1 :
+true
+
+Sample Input 2 :
+3
+1 0 1
+1 0 1
+0 1 1
+Sample Output 2 :
+false
+*/
+
+public class Solution {
+    
+	public static boolean ratInAMaze(int maze[][]){
+
+		/*Your class should be named Solution. 
+		*Don't write main().
+	 	*Don't take input, it is passed as function argument.
+	 	*Don't print output.
+	 	*Taking input and printing output is handled automatically.
+		*/ 
+		int path[][] = new int[maze.length][maze.length];
+		return solveMaze(maze,0,0,path);
+	}
+    
+    public static boolean solveMaze(int[][] maze, int i, int j, int[][] path)
+	{
+		//Check if i,j are valid pair of indices => i,j>=0
+		int n=maze.length;
+		if (i<0 || j<0 || i>=n || j>=n)
+			return false;
+		
+		//If cell is already part of the path
+		if (path[i][j]==1)
+			return false;
+		
+		//If cell is blocked in maze (cell value=0)
+		if (maze[i][j]==0)
+			return false;
+		
+		//If all previous conditions fail, then the cell is a possible path
+		//Include the cell in current path
+		path[i][j]=1;
+		
+		//If we have reached ending point 
+		if (i==n-1 && j==n-1)
+			return true;
+		
+		//Now, explore in all directions
+		// Direction 1 - move towards cell above (top direction)
+		if (solveMaze(maze,i-1,j,path))
+			return true;
+		
+		//Direction 2 - move towards cell to the right (right direction)
+		if (solveMaze(maze,i,j+1,path))
+			return true;
+		
+		//Direction 3 - move towards cell below (bottom direction)
+		if (solveMaze(maze,i+1,j,path))
+			return true;
+		
+		//Direction 3 - move towards cell to the left (left direction)
+		if (solveMaze(maze,i,j-1,path))
+			return true;
+		
+		//If none of the conditions are satisfied, then the path is not working out
+		return false;
+	}
+}