coded + unit tested

Author: Ram swaroop

src/me/ramswaroop/backtracking/KnightTour.java

@@ -15,22 +15,20 @@
 public class KnightTour {
 
     /**
-     * 
      * @param i
      * @param j
      * @param tour
      * @return
      */
     public static boolean isValidMove(int i, int j, int[][] tour) {
-        if (i >= 0 && j >= 0 && i < tour.length && j < tour[0].length && tour[i][j] == 0) {
+        if (i >= 0 && i < tour.length && j >= 0 && j < tour[0].length && tour[i][j] == 0) {
             return true;
         } else {
             return false;
         }
     }
 
     /**
-     * 
      * @param i
      * @param j
      * @param xMoves
@@ -43,9 +41,11 @@ public static boolean isValidKnightTour(int i, int j, int[] xMoves, int[] yMoves
 
         if (step > tour.length * tour[0].length) return true;
 
+        int nextI, nextJ;
+
         for (int k = 0; k < xMoves.length; k++) {
-            int nextI = i + xMoves[k];
-            int nextJ = j + yMoves[k];
+            nextI = i + xMoves[k];
+            nextJ = j + yMoves[k];
 
             if (isValidMove(nextI, nextJ, tour)) {
                 tour[nextI][nextJ] = step;
@@ -61,7 +61,6 @@ public static boolean isValidKnightTour(int i, int j, int[] xMoves, int[] yMoves
     }
 
     /**
-     * 
      * @param boardSize
      */
     public static void printKnightTour(int[] boardSize) {

src/me/ramswaroop/backtracking/RatInAMaze.java

@@ -0,0 +1,72 @@
+package me.ramswaroop.backtracking;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 10/18/15
+ * @time: 10:39 AM
+ */
+public class RatInAMaze {
+
+    public static boolean isValidMove(int i, int j, int[][] maze) {
+        if (i >= 0 && i < maze.length && j >= 0 && j < maze[0].length && maze[i][j] == 1) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    public static boolean isValidPath(int i, int j, int[] xMoves, int[] yMoves, int[][] maze, int[][] path) {
+
+        if (i == maze.length - 1 && j == maze[0].length - 1) return true;
+
+        int nextI, nextJ;
+
+        for (int k = 0; k < xMoves.length; k++) {
+            nextI = i + xMoves[k];
+            nextJ = j + yMoves[k];
+            if (isValidMove(nextI, nextJ, maze)) {
+                path[nextI][nextJ] = 1;
+                if (isValidPath(nextI, nextJ, xMoves, yMoves, maze, path)) {
+                    return true;
+                } else {
+                    path[nextI][nextJ] = 0;
+                }
+            }
+        }
+        return false;
+    }
+
+    public static void printMazePath(int i, int j, int[][] maze) {
+
+        int[] xMoves = {0, 1};
+        int[] yMoves = {1, 0};
+        
+        int[][] path = new int[maze.length][maze[0].length];
+        
+        System.out.println("Maze");
+        System.out.println("---------------");
+        print2DMatrix(maze);
+        System.out.println("---------------");
+
+        if (isValidPath(i, j, xMoves, yMoves, maze, path)) {
+            print2DMatrix(path);
+        } else {
+            System.out.println("No escape path found!");
+        }
+    }
+
+    public static void print2DMatrix(int[][] array) {
+        for (int i = 0; i < array.length; i++) {
+            for (int j = 0; j < array[0].length; j++) {
+                System.out.print("[" + array[i][j] + "]");
+            }
+            System.out.println();
+        }
+    }
+
+    public static void main(String a[]) {
+        printMazePath(0, 0, new int[][]{{1, 1, 1, 1}, {0, 0, 1, 1}});
+    }
+}