Create WordSearch.java

Author: 17tanya

Backtracking/WordSearch.java

@@ -0,0 +1,35 @@
+//LeetCode 79. Word Search
+//Question - https://leetcode.com/problems/word-search/
+
+class Solution {
+    public boolean exist(char[][] board, String word) {
+        
+        for(int i = 0 ; i < board.length ; i++){
+            for(int j = 0 ; j < board[0].length ; j++){
+                if(helper(board, i, j, word, 0)) return true;
+            }
+        }
+        return false;
+    }
+    
+    public boolean helper(char[][] b, int x, int y, String s, int end){
+        //Base Cases
+        if(end == s.length()) return true;
+        
+        if(x < 0 || x >= b.length || y < 0 || y >= b[0].length) return false;
+        if(b[x][y] != s.charAt(end)) return false;
+        
+        //Mark as visited
+        b[x][y] = '#';
+        
+        //go deeper into recursion
+        boolean res = helper(b, x+1, y, s, end+1) ||
+                      helper(b, x-1, y, s, end+1) ||
+                      helper(b, x, y+1, s, end+1) ||
+                      helper(b, x, y-1, s, end+1);
+        //backtarck
+        b[x][y] = s.charAt(end);
+        
+        return res;
+    }
+}