feat(soobing): week14 > word-search-ii

Author: soobing

word-search-ii/soobing.ts

@@ -0,0 +1,83 @@
+/**
+ * 문제 설명
+ * - 2차원 배열에서 주어진 단어들을 찾는 문제
+ *
+ * 아이디어
+ * 1) Trie 자료구조 + DFS & Backtracking (👀어려웠음..다시 풀어보기)
+ *   - 주어진 단어들을 Trie 자료구조로 변환
+ *   - 2차원 배열을 순회하면서 Trie 자료구조를 사용하여 단어를 찾음
+ *   - 찾은 단어는 배열에 추가
+ */
+class TrieNode {
+  private nodes = new Map<string, TrieNode>();
+  word: string | null = null;
+
+  add(word: string) {
+    let currentNode = this as TrieNode;
+    for (const char of word) {
+      if (!currentNode.nodes.has(char)) {
+        currentNode.nodes.set(char, new TrieNode());
+      }
+      currentNode = currentNode.nodes.get(char)!;
+    }
+    currentNode.word = word;
+  }
+
+  getNode(char: string) {
+    return this.nodes.get(char);
+  }
+
+  hasChar(char: string) {
+    return this.nodes.has(char);
+  }
+}
+
+function search(
+  m: number,
+  n: number,
+  board: string[][],
+  node: TrieNode,
+  result: string[]
+) {
+  const M = board.length;
+  const N = board[0].length;
+  if (m < 0 || m >= M || n < 0 || n >= N) return;
+
+  const currentChar = board[m][n];
+  if (currentChar === "#" || !node.hasChar(currentChar)) return;
+
+  node = node.getNode(currentChar)!;
+
+  if (node.word) {
+    result.push(node.word);
+    node.word = null;
+  }
+
+  board[m][n] = "#";
+
+  search(m + 1, n, board, node, result);
+  search(m - 1, n, board, node, result);
+  search(m, n + 1, board, node, result);
+  search(m, n - 1, board, node, result);
+
+  board[m][n] = currentChar;
+}
+
+function findWords(board: string[][], words: string[]): string[] {
+  const root = new TrieNode();
+  for (const word of words) {
+    root.add(word);
+  }
+
+  const result: string[] = [];
+  const M = board.length;
+  const N = board[0].length;
+
+  for (let i = 0; i < M; i++) {
+    for (let j = 0; j < N; j++) {
+      search(i, j, board, root, result);
+    }
+  }
+
+  return result;
+}