word search ii solution

Author: hyer0705

word-search-ii/hyer0705.ts

@@ -0,0 +1,176 @@
+// 84ms
+class TrieNode {
+  children: Map<string, TrieNode>;
+  isEndOf: boolean;
+  word: string | null;
+
+  constructor() {
+    this.children = new Map();
+    this.word = null;
+  }
+}
+class Trie {
+  root: TrieNode;
+
+  constructor() {
+    this.root = new TrieNode();
+  }
+
+  insert(word: string) {
+    let current = this.root;
+
+    for (const char of word) {
+      if (!current.children.has(char)) {
+        current.children.set(char, new TrieNode());
+      }
+      current = current.children.get(char);
+    }
+
+    current.word = word;
+  }
+}
+
+function findWords(board: string[][], words: string[]): string[] {
+  const m = board.length;
+  const n = board[0].length;
+
+  const dictionary = new Trie();
+  for (const word of words) {
+    dictionary.insert(word);
+  }
+
+  const results: string[] = [];
+
+  const dfs = (row: number, col: number, trieNode: TrieNode) => {
+    if (trieNode.word !== null) {
+      results.push(trieNode.word);
+      trieNode.word = null;
+    }
+
+    const directions = [
+      [-1, 0],
+      [1, 0],
+      [0, -1],
+      [0, 1],
+    ];
+
+    for (const [dr, dc] of directions) {
+      const [nr, nc] = [row + dr, col + dc];
+
+      if (nr >= 0 && nr < m && nc >= 0 && nc < n) {
+        if (trieNode.children.has(board[nr][nc])) {
+          const char = board[nr][nc];
+          const childNode = trieNode.children.get(char);
+
+          if (board[nr][nc] !== "#") {
+            board[nr][nc] = "#";
+            dfs(nr, nc, trieNode.children.get(char));
+            board[nr][nc] = char;
+          }
+
+          if (childNode.children.size === 0 && childNode.word === null) {
+            trieNode.children.delete(char);
+          }
+        }
+      }
+    }
+  };
+
+  for (let i = 0; i < m; i++) {
+    for (let j = 0; j < n; j++) {
+      const firstChar = board[i][j];
+      if (dictionary.root.children.has(firstChar)) {
+        board[i][j] = "#";
+        dfs(i, j, dictionary.root.children.get(firstChar));
+        board[i][j] = firstChar;
+      }
+    }
+  }
+
+  return results;
+}
+
+// 2312ms
+class TrieNode {
+  children: Map<string, TrieNode>;
+  word: string | null;
+
+  constructor() {
+    this.children = new Map();
+    this.word = null;
+  }
+}
+class Trie {
+  root: TrieNode;
+
+  constructor() {
+    this.root = new TrieNode();
+  }
+
+  insert(word: string) {
+    let current = this.root;
+
+    for (const char of word) {
+      if (!current.children.has(char)) {
+        current.children.set(char, new TrieNode());
+      }
+      current = current.children.get(char)!;
+    }
+
+    current.word = word;
+  }
+}
+
+function findWords(board: string[][], words: string[]): string[] {
+  const m = board.length;
+  const n = board[0].length;
+
+  const dictionary = new Trie();
+  for (const word of words) {
+    dictionary.insert(word);
+  }
+
+  const results: string[] = [];
+
+  const dfs = (row: number, col: number, trieNode: TrieNode, path: string) => {
+    if (trieNode.word === path) {
+      results.push(path);
+      trieNode.word = null;
+    }
+
+    const directions = [
+      [-1, 0],
+      [1, 0],
+      [0, -1],
+      [0, 1],
+    ];
+
+    for (const [dr, dc] of directions) {
+      const [nr, nc] = [row + dr, col + dc];
+
+      if (nr >= 0 && nr < m && nc >= 0 && nc < n) {
+        if (trieNode.children.has(board[nr][nc])) {
+          if (!isVisited.has(`${nr},${nc}`)) {
+            isVisited.add(`${nr},${nc}`);
+            dfs(nr, nc, trieNode.children.get(board[nr][nc])!, path + board[nr][nc]);
+            isVisited.delete(`${nr},${nc}`);
+          }
+        }
+      }
+    }
+  };
+
+  const isVisited = new Set<string>(); // 'r,c'
+  for (let i = 0; i < m; i++) {
+    for (let j = 0; j < n; j++) {
+      const firstChar = board[i][j];
+      if (dictionary.root.children.has(firstChar)) {
+        isVisited.add(`${i},${j}`);
+        dfs(i, j, dictionary.root.children.get(firstChar)!, firstChar);
+        isVisited.delete(`${i},${j}`);
+      }
+    }
+  }
+
+  return results;
+}