feat: word-search-ii

Author: gwbaik9717

word-search-ii/gwbaik9717.js

@@ -0,0 +1,79 @@
+// n: length of words, k: length of word, h: height of board, w: width of board
+// Time complexity: O(4^k * h * w * n)
+// Space complexity: O(4^k)
+
+/**
+ * @param {character[][]} board
+ * @param {string[]} words
+ * @return {string[]}
+ */
+var findWords = function (board, words) {
+  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 }, () => false)
+  );
+
+  const findWord = (current, i, word) => {
+    const [cy, cx] = current;
+
+    if (i === word.length - 1) {
+      return true;
+    }
+
+    let found = false;
+
+    for (let j = 0; j < dx.length; j++) {
+      const nx = cx + dx[j];
+      const ny = cy + dy[j];
+
+      if (nx >= 0 && nx < w && ny >= 0 && ny < h && !checked[ny][nx]) {
+        if (board[ny][nx] === word[i + 1]) {
+          checked[ny][nx] = true;
+
+          if (findWord([ny, nx], i + 1, word)) {
+            found = true;
+          }
+
+          checked[ny][nx] = false;
+        }
+      }
+    }
+
+    return found;
+  };
+
+  const answer = [];
+
+  for (const word of words) {
+    let found = false;
+
+    for (let i = 0; i < h; i++) {
+      if (found) {
+        break;
+      }
+
+      for (let j = 0; j < w; j++) {
+        if (found) {
+          break;
+        }
+
+        if (board[i][j] === word[0]) {
+          checked[i][j] = true;
+
+          if (findWord([i, j], 0, word)) {
+            answer.push(word);
+            found = true;
+          }
+
+          checked[i][j] = false;
+        }
+      }
+    }
+  }
+
+  return answer;
+};