79. Word Search (java)

Author: bluesword12350

solution/0079.Word Search/Solution.java

@@ -0,0 +1,30 @@
+class Solution {
+    private char[] cs;
+    private char[][] board;
+    public boolean exist(char[][] board, String word) {
+        this.cs = word.toCharArray();
+        this.board = board;
+        for (int i = 0; i < board.length; i++) {
+            for (int j = 0; j < board[i].length; j++) {
+                if (board[i][j] == cs[0] && backtrack(i, j, 0)) return true;
+            }
+        }
+        return false;
+    }
+    private boolean backtrack(int i, int j, int k) {
+        if (board[i][j] == cs[k]) {
+            if (k == cs.length - 1) return true;
+            char cache = board[i][j];
+            board[i][j] = 0;
+            k++;
+            if ( i > 0 && backtrack(i - 1, j, k)
+                    || i < board.length - 1 && backtrack(i + 1, j, k)
+                    || j > 0 && backtrack(i, j - 1, k)
+                    || j < board[i].length - 1 && backtrack(i, j + 1, k)) {
+                return true;
+            }
+            board[i][j] = cache;
+        }
+        return false;
+    }
+}