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Commit b71081b

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‎Java/290.word-pattern.java

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/*
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* @lc app=leetcode id=290 lang=java
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*
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* [290] Word Pattern
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*/
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// @lc code=start
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class Solution {
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/*
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time: O(n^2) containsValue() costs O(n)
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space: O(n)
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*/
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public boolean wordPattern(String pattern, String str) {
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String[] words = str.split(" ");
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if (pattern.length() != words.length) return false;
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Map<String, Character> map = new HashMap<>();
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for (int i = 0; i < pattern.length(); ++i) {
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if (map.containsKey(words[i])) {
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if (pattern.charAt(i) != map.get(words[i])) {
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return false;
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}
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} else if (map.containsValue(pattern.charAt(i))) {
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return false;
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} else {
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map.put(words[i], pattern.charAt(i));
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}
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}
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return true;
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}
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}
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// @lc code=end
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/*
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* @lc app=leetcode id=642 lang=java
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*
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* [642] Design Search Autocomplete System
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*/
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// @lc code=start
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/*
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Trie记录前缀搜索的字符
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对于每一个字符,利用一个hashmap来记录与之有关的字符串和对应的count
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input的时候利用一个PriorityQueue来返回count最大的三个结果
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time: O(nl) for building the trie, n = number of sentences and l = avg length of sentence
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O(l + mlogm) m = size of map
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space: O(nl) and memory of each map
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*/
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class AutocompleteSystem {
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class TrieNode {
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TrieNode[] children;
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Map<String, Integer> count;
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public TrieNode() {
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children = new TrieNode[128];
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count = new HashMap<>();
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}
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}
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class Pair {
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String key;
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int count;
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public Pair(String key, int count) {
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this.key = key;
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this.count = count;
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}
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}
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TrieNode root;
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StringBuilder sb;
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public AutocompleteSystem(String[] sentences, int[] times) {
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root = new TrieNode();
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sb = new StringBuilder();
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for (int i = 0; i < sentences.length; ++i) {
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add(sentences[i], times[i]);
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}
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}
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public List<String> input(char c) {
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List<String> res = new ArrayList<>();
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if (c == '#') {
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add(sb.toString(), 1);
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sb.setLength(0);
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return res;
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}
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sb.append(c);
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TrieNode cur = root;
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for (int i = 0; i < sb.length(); ++i) {
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if (cur.children[sb.charAt(i)] == null) return res;
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cur = cur.children[sb.charAt(i)];
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}
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PriorityQueue<Pair> pq = new PriorityQueue<>((a, b) ->
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a.count == b.count ? a.key.compareTo(b.key) : b.count - a.count);
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for (String key : cur.count.keySet()) {
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pq.add(new Pair(key, cur.count.get(key)));
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}
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for (int i = 0; i < 3 && !pq.isEmpty(); ++i) {
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res.add(pq.poll().key);
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}
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return res;
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}
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private void add(String sentence, int times) {
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TrieNode cur = root;
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for (char c : sentence.toCharArray()) {
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if (cur.children[c] == null) {
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cur.children[c] = new TrieNode();
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}
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cur = cur.children[c];
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cur.count.put(sentence, cur.count.getOrDefault(sentence, 0) + times);
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}
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}
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}
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/**
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* Your AutocompleteSystem object will be instantiated and called as such:
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* AutocompleteSystem obj = new AutocompleteSystem(sentences, times);
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* List<String> param_1 = obj.input(c);
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*/
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// @lc code=end
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‎README.md

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:- | :-:
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[146. LRU Cache](https://leetcode.com/problems/lru-cache/) | [HashMap + Doubly Linked List](https://github.com/Yukinichi/leetcode/blob/master/Java/146.lru-cache.java) \| [Java LinkedHashMap](https://github.com/Yukinichi/leetcode/blob/master/Java/146.lru-cache-solution2.java)
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[460. LFU Cache](https://leetcode.com/problems/lfu-cache/) | [HashMap + TreeSet(Ologn)](https://github.com/Yukinichi/leetcode/blob/master/Java/460.lfu-cache.java) \| [HashMap + DList(O(1))](https://github.com/Yukinichi/leetcode/blob/master/Java/460.lfu-cache-2.java)
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[642. Design Search Autocomplete System](https://leetcode.com/problems/design-search-autocomplete-system/) | [Trie + PriorityQueue](https://github.com/Yukinichi/leetcode/blob/master/Java/642.design-search-autocomplete-system.java)
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[895. Maximum Frequency Stack](https://leetcode.com/problems/maximum-frequency-stack/) | [思路同LFU Cache](https://github.com/Yukinichi/leetcode/blob/master/Java/895.maximum-frequency-stack.java)
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[705. Design HashSet](https://leetcode.com/problems/design-hashset/) | [linkedlist handle hashing collision](https://github.com/Yukinichi/leetcode/blob/master/Java/705.design-hash-set.java)
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[706. Design HashMap](https://leetcode.com/problems/design-hashmap/) | [linkedlist handle hashing collision](https://github.com/Yukinichi/leetcode/blob/master/Java/706.design-hash-map.java)

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