leetcode-451-根据字符出现频率排序
//有一些字符串的处理,题目大小写敏感
bool cmp(pair<char, int> a, pair<char, int> b) {
return (a.second > b.second);
}
class Solution {
public:
string frequencySort(string s) {
int N = s.length(), k=0;
string res = "";
map<char, int> freq;
vector<pair<char, int>> resvec;
for (int i = 0; i < N; i++) {
freq[s[i]]++;
}
for (auto it = freq.begin(); it != freq.end(); it++) {
resvec.push_back(make_pair(it->first, it->second));
}
sort(resvec.begin(), resvec.end(), cmp);
for (auto it = resvec.begin(); it != resvec.end(); it++){
res.append(it->second,it->first);
}
return res;
}
};
int main()
{
Solution sol;
string input = "treeeab";
cout << sol.frequencySort(input);
cout<< endl;
return 0;
}