Word Search

Author: Sunjae95

word-search/sunjae95.js

@@ -0,0 +1,57 @@
+/**
+ * @description
+ * brainstorming:
+ * dfs
+ *
+ * time complexity: O(n^2 * 4^word.length)
+ * space complexity: O(n^2)
+ */
+
+var exist = function (board, word) {
+  let answer = false;
+  const ROW_LENGTH = board.length;
+  const COLUMN_LENGTH = board[0].length;
+  // O(n^2)
+  const visited = Array.from({ length: ROW_LENGTH }, () =>
+    Array.from({ length: COLUMN_LENGTH }, () => false)
+  );
+
+  const isRange = (r, c) =>
+    r >= 0 && r < ROW_LENGTH && c >= 0 && c < COLUMN_LENGTH && !visited[r][c];
+
+  const search = (r, c, currentWord) => {
+    if (answer) return;
+    if (currentWord.length > word.length) return;
+    if (!word.includes(currentWord)) return;
+    if (currentWord === word) {
+      answer = true;
+      return;
+    }
+
+    const dr = [-1, 0, 0, 1];
+    const dc = [0, -1, 1, 0];
+
+    for (let i = 0; i < 4; i++) {
+      const nextR = r + dr[i];
+      const nextC = c + dc[i];
+
+      if (!isRange(nextR, nextC)) continue;
+
+      const nextWord = currentWord + board[nextR][nextC];
+
+      visited[nextR][nextC] = true;
+      search(nextR, nextC, nextWord);
+      visited[nextR][nextC] = false;
+    }
+  };
+
+  for (let r = 0; r < ROW_LENGTH; r++) {
+    for (let c = 0; c < COLUMN_LENGTH; c++) {
+      visited[r][c] = true;
+      search(r, c, board[r][c]);
+      visited[r][c] = false;
+    }
+  }
+
+  return answer;
+};