软件开发工程师属于什么行业_市场营销的十大理论_杭州小程序建设公司_百度指数功能

1. 题目

2. 思路和题解

这道题和昨天那道347题一样，也是用桶排序来做。主要步骤如下：

1. 遍历字符串，统计每个字符出现的频率，同时记录最高频率 maxFreq
2. 创建桶，存储从 1 到 maxFreq 的每个出现频率的字符
3. 按照出现频率从大到小的顺序遍历桶，对于每个出现频率，获得对应的字符，然后将每个字符按照出现频率拼接到排序后的字符串

所以整体的代码如下：

class Solution {public String frequencySort(String s) {Map<Character, Integer> map = new HashMap<Character, Integer>();int maxFreq = 0;int length = s.length();for (int i = 0; i < length; i++) {char c = s.charAt(i);int frequency = map.getOrDefault(c, 0) + 1;map.put(c, frequency);maxFreq = Math.max(maxFreq, frequency);}StringBuffer[] buckets = new StringBuffer[maxFreq + 1];for (int i = 0; i <= maxFreq; i++) {buckets[i] = new StringBuffer();}for (Map.Entry<Character, Integer> entry : map.entrySet()) {char c = entry.getKey();int frequency = entry.getValue();buckets[frequency].append(c);}StringBuffer sb = new StringBuffer();for (int i = maxFreq; i > 0; i--) {StringBuffer bucket = buckets[i];int size = bucket.length();for (int j = 0; j < size; j++) {for (int k = 0; k < i; k++) {sb.append(bucket.charAt(j));}}}return sb.toString();}
}