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0079-word-search/0079-word-search.java

@@ -0,0 +1,45 @@
+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 (board[i][j] == word.charAt(0)) {
+                    if (search(0, i, j, board, word, new boolean[board.length][board[0].length])) {
+                        return true;
+                    }
+                }
+            }
+        }
+
+        return false;
+    }
+
+    private boolean search(int index, int x, int y, char[][] board, String word, boolean[][] visited) {
+        if (index == word.length()) {
+            return true;
+        }
+
+        if (x < 0 || x >= board.length || y < 0 || y >= board[0].length) {
+            return false;
+        }
+
+        if (visited[x][y]) {
+            return false;
+        }
+
+        if (board[x][y] != word.charAt(index)) {
+            return false;
+        }
+
+        visited[x][y] = true;
+        if (search(index + 1, x + 1, y, board, word, visited) ||
+            search(index + 1, x, y + 1, board, word, visited) ||
+            search(index + 1, x - 1, y, board, word, visited) ||
+            search(index + 1, x, y - 1, board, word, visited)) {
+            return true;
+        }
+        visited[x][y] = false;
+
+        return false;
+    }
+}