var findWords = function(grid, words) {
// 存放最终结果集
let res = []
// 字典树节点
class TrieNode {
constructor(){
this.end = false
this.child = {
}
}
}
// 最终形成的字典树根节点
let root = null
let Trie = function(){
root = new TrieNode()
}
// 建立字典树
Trie.prototype.insert = (word) => {
let cur = root
for(let i=0;i<word.length;i++){
if(!cur.child[word[i]]){
cur.child[word[i]] = new TrieNode()
}
cur = cur.child[word[i]]
}
cur.end = true
}
// 在 Trie 树中查找键
let searchPrefix = (word) => {
let cur = root
for(let i=0;i<word.length;i++){
if(cur.child[word[i]]){
cur = cur.child[word[i]]
}else{
return null
}
}
return cur
}
Trie.prototype.search = (word) => {
let cur = searchPrefix(word)
return cur !== null && cur.end
}
// 查找 Trie 树中的键前缀
Trie.prototype.startsWith = (pre) => {
return searchPrefix(pre) != null
}
// 创建根节点
let trie = new Trie()
// 进行建树操作
for(let i=0;i<words.length;i++){
trie.insert(words[i])
}
let dfs = (x,y,t,cur) => {
if(cur.end){
res.push(t)
cur.end = false // 避免重复计算
}
// 剪枝条件:1.边界处理 2.下一步是否可走 3.下一步字典树是否可走
if(x<0 || x>=grid.length || y<0 || y>=grid[0].length || grid[x][y] == '#' || !cur.child[grid[x][y]]) return
let tmp = grid[x][y]
grid[x][y] = '#' // 走
cur = cur.child[tmp]
dfs(x+1,y,t+tmp,cur) // 上下左右四个方向遍历
dfs(x,y+1,t+tmp,cur)
dfs(x-1,y,t+tmp,cur)
dfs(x,y-1,t+tmp,cur)
grid[x][y] = tmp // 回溯(还原)
}
// 对单词表进行全局搜索
for(let i=0;i<grid.length;i++){
for(let j=0;j<grid[0].length;j++){
dfs(i,j,'',root)
}
}
return res
};
let words = ["oath","pea","eat","rain"]
let grid =
[
['o','a','a','n'],
['e','t','a','e'],
['i','h','k','r'],
['i','f','l','v']
]
console.log(findWords(grid,words)) //[ 'oath', 'eat' ]
【leetcode】JS 字典树 建树 查找键 查找键前缀【模板】
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转载自blog.csdn.net/weixin_42429718/article/details/108563711
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