Rat_in_a_Maze

Backtracking/Rat_in_a_Maze.py

@@ -0,0 +1,69 @@
+# Maze size
+N = 4
+
+def printSolution( sol ):
+
+    for i in sol:
+        for j in i:
+            print(str(j) + " ", end ="")
+        print("")
+
+def isSafe( maze, x, y ):
+    if x >= 0 and x < N and y >= 0 and y < N and maze[x][y] == 1:
+        return True
+
+    return False
+
+def solveMaze( maze ):
+    # Creating a 4 * 4 2-D list
+    sol = [ [ 0 for j in range(4) ] for i in range(4) ]
+
+    if solveMazeUtil(maze, 0, 0, sol) == False:
+        print("Solution doesn't exist");
+        return False
+    printSolution(sol)
+    return True
+
+def solveMazeUtil(maze, x, y, sol):
+    # if (x, y is goal) return True
+    if x == N - 1 and y == N - 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) == True:
+            return True
+
+        # If moving in x direction doesn't give solution
+        # then Move down in y direction
+        if solveMazeUtil(maze, x, y + 1, sol) == True:
+            return True
+
+        # If none of the above movements work then
+        # BACKTRACK: unmark x, y as part of solution path
+        sol[x][y] = 0
+        return False
+
+# Main Program
+if __name__ == "__main__":
+    # Initialising the maze
+    maze = [ [1, 0, 0, 0],
+             [1, 1, 0, 1],
+             [0, 1, 0, 0],
+             [1, 1, 1, 1] ]
+
+    solveMaze(maze)
+'''  
+==============
+Output:
+1 0 0 0 
+1 1 0 0 
+0 1 0 0 
+0 1 1 1
+==============
+'''