feat: word-search solution

Author: sm9171

word-search/sm9171.java

@@ -0,0 +1,42 @@
+class Solution {
+    public boolean exist(char[][] board, String word) {
+        if (board == null || board.length == 0 || word == null || word.length() == 0) {
+            return false;
+        }
+
+        int rows = board.length;
+        int cols = board[0].length;
+        boolean[][] visited = new boolean[rows][cols];
+
+        for (int i = 0; i < rows; i++) {
+            for (int j = 0; j < cols; j++) {
+                if (dfs(board, visited, i, j, word, 0)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    private static boolean dfs(char[][] board, boolean[][] visited, int i, int j, String word, int index) {
+        if (index == word.length()) {
+            return true;
+        }
+
+        if (i < 0 || i >= board.length || j < 0 || j >= board[0].length || visited[i][j] || board[i][j] != word.charAt(index)) {
+            return false;
+        }
+
+
+        visited[i][j] = true;
+
+        boolean found = dfs(board, visited, i + 1, j, word, index + 1) ||
+                dfs(board, visited, i - 1, j, word, index + 1) ||
+                dfs(board, visited, i, j + 1, word, index + 1) ||
+                dfs(board, visited, i, j - 1, word, index + 1);
+
+        visited[i][j] = false;
+
+        return found;
+    }
+}