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212.单词搜索-ii.js
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212.单词搜索-ii.js
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/*
* @lc app=leetcode.cn id=212 lang=javascript
*
* [212] 单词搜索 II
*/
// @lc code=start
/**
* @param {character[][]} board
* @param {string[]} words
* @return {string[]}
*/
var findWords = function(board, words) {
const Trie = function() {
this.root = new TrieNode();
}
const TrieNode = function() {
this.children = {};
this.data = '';
this.isEndingChar = false;
}
Trie.prototype.insert = function(word) {
let node = this.root;
for (let i = 0; i < word.length; i++) {
const letter = word[i];
if (!node.children[letter]) {
const newNode = new TrieNode();
newNode.data = node.data + letter;
node.children[letter] = newNode;
}
node = node.children[letter];
}
node.isEndingChar = true;
}
const result = [];
const x = [-1, 1, 0, 0];
const y = [0, 0, -1, 1];
// 构建单词 Trie 树
const wordsTrie = new Trie();
const len = words.length;
for (let i = 0; i < len; i++) {
wordsTrie.insert(words[i]);
}
let row = board.length;
let col = board[0].length;
for (let i = 0; i < row; i++) {
for (let j = 0; j < col; j++) {
search(wordsTrie.root, i, j)
}
}
function search (node, i, j) {
if (node.isEndingChar) {
result.push(node.data);
node.isEndingChar = false;
}
// 越界退出
if (i < 0 || i >= row || j < 0 || j >= col) return;
const letter = board[i][j];
if (!node.children[letter]) return;
board[i][j] = '#';
for (let d = 0; d < x.length; d++) {
search(node.children[letter], i+y[d], j+x[d]);
}
board[i][j] = letter;
}
return result;
};
// var findWords = function (board, words) {
// let res = [];
// // 上下左右四个方位,便于多个方向查找
// const x = [-1, 1, 0, 0];
// const y = [0, 0, -1, 1];
// function buildTrie() {
// const root = {};
// for (let w of words) {
// let node = root;
// for (let c of w) {
// if (!node[c]) node[c] = {};
// node = node[c];
// };
// // 在节点的末尾村上单词
// node.word = w;
// }
// return root;
// }
// function search(node, i, j) {
// if (node.word) {
// res.push(node.word);
// node.word = null; // 找到word 后设置为null
// }
// // 越界的情况,直接返回
// if (i < 0 || i >= board.length || j < 0 || j >= board[i].length) return;
// // 如果首字母在trie 中找不到
// if (node[board[i][j]] == null) return;
// const c = board[i][j];
// // 防止重复查找,先设置#后面赋值回来
// board[i][j] = "#";
// for (let d = 0; d < x.length; d++) {
// search(node[c], i + y[d], j + x[d]);
// }
// board[i][j] = c;
// }
// // 将单词源变成trie
// const root = buildTrie();
// for (let i = 0; i < board.length; i++) {
// for (let j = 0; j < board[i].length; j++) {
// search(root, i, j);
// }
// }
// return res;
// };
// @lc code=end