C++ | Leetcode C++题解之第451题根据字符出现频率排序
题目：
题解：
class Solution {
public:
string frequencySort(string s) {
unordered_map<char, int> mp;
int maxFreq = 0;
int length = s.size();
for (auto &ch : s) {
maxFreq = max(maxFreq, ++mp[ch]);
}
vector<string> buckets(maxFreq + 1);
for (auto &[ch, num] : mp) {
buckets[num].push_back(ch);
}
string ret;
for (int i = maxFreq; i > 0; i--) {
string &bucket = buckets[i];
for (auto &ch : bucket) {
for (int k = 0; k < i; k++) {
ret.push_back(ch);
}
}
}
return ret;
}
};