feat: 79. Word Search

Author: gwbaik9717

word-search/gwbaik9717.js

@@ -0,0 +1,62 @@
+// h: height of the board, w: width of the board, n: length of the word
+// Time complexity: O(h * w * 4**n)
+// Space complexity: O(h * w + n)
+
+/**
+ * @param {character[][]} board
+ * @param {string} word
+ * @return {boolean}
+ */
+var exist = function (board, word) {
+  const n = word.length;
+  const h = board.length;
+  const w = board[0].length;
+
+  const dy = [1, 0, -1, 0];
+  const dx = [0, 1, 0, -1];
+
+  const checked = Array.from({ length: h }, () =>
+    Array.from({ length: w }, () => 0)
+  );
+
+  let answer = false;
+
+  const dfs = (current, index) => {
+    if (index === n - 1) {
+      answer = true;
+      return;
+    }
+
+    const [cy, cx] = current;
+    checked[cy][cx] = 1;
+
+    for (let i = 0; i < dy.length; i++) {
+      const ny = cy + dy[i];
+      const nx = cx + dx[i];
+      const ni = index + 1;
+
+      if (
+        ny >= 0 &&
+        ny < h &&
+        nx >= 0 &&
+        nx < w &&
+        checked[ny][nx] === 0 &&
+        word[ni] === board[ny][nx]
+      ) {
+        dfs([ny, nx], ni);
+      }
+    }
+
+    checked[cy][cx] = 0;
+  };
+
+  for (let i = 0; i < h; i++) {
+    for (let j = 0; j < w; j++) {
+      if (board[i][j] === word[0] && !answer) {
+        dfs([i, j], 0);
+      }
+    }
+  }
+
+  return answer;
+};