692. Top K Frequent Words
Posted johnnyzhao
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了692. Top K Frequent Words相关的知识,希望对你有一定的参考价值。
package LeetCode_692 import java.util.* import kotlin.collections.ArrayList import kotlin.collections.HashMap /** * 692. Top K Frequent Words * https://leetcode.com/problems/top-k-frequent-words/description/ * * Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first. Example 1: Input: ["i", "love", "leetcode", "i", "love", "coding"], k = 2 Output: ["i", "love"] Explanation: "i" and "love" are the two most frequent words. Note that "i" comes before "love" due to a lower alphabetical order. Example 2: Input: ["the", "day", "is", "sunny", "the", "the", "the", "sunny", "is", "is"], k = 4 Output: ["the", "is", "sunny", "day"] Explanation: "the", "is", "sunny" and "day" are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Input words contain only lowercase letters. Follow up: Try to solve it in O(n log k) time and O(n) extra space. * */ class Solution { /* * solution 1: HashMap+PriorityQueue, Time complexity:O(nlogk), Space complexity:O(n) * */ fun topKFrequent(words: Array<String>, k: Int): List<String> { val map = HashMap<String, Int>() for (word in words) { map.put(word, map.getOrDefault(word, 0) + 1) } val queue = PriorityQueue<Pair<String, Int>> { a, b -> if (a.second == b.second) { //if frequency is same, take the alphabetical desc, because the result need reverse it b.first.compareTo(a.first) } else { //take the frequency asc, because the result need reverse it also a.second - b.second } } for (item in map) { queue.offer(Pair(item.key, item.value)) if (queue.size > k) { queue.remove() } } val result = ArrayList<String>() while (queue.isNotEmpty()) { result.add(0, queue.poll().first) } return result } }
以上是关于692. Top K Frequent Words的主要内容,如果未能解决你的问题,请参考以下文章
347. Top K Frequent Elements/692. Top K Frequent Words