题解 | #删除字符串中出现次数最少的字符#

#include <climits>
#include <iostream>
#include <map>
#include <vector>
#include <algorithm>

using namespace std;
typedef pair<int,char> T;

vector<T> SortByVal(map<char, int> hashMap)
{
    vector<T> vec;
    for (auto it = hashMap.begin(); it != hashMap.end(); it++){
        vec.push_back(make_pair( it->second, it->first));
    }
    sort(vec.begin(), vec.end()); 
    return vec;
}

int main() {
    map<char,int> hashMap;

    string s;
    getline(cin,s);

    int min = INT_MAX;
    for (int i = 0; i < s.length(); i++){
        auto it = hashMap.find(s[i]);
        if (it == hashMap.end()){
            hashMap[s[i]] = 1;
        }
        else{
            hashMap[s[i]] += 1;
        }
    }
    
    vector<T> vec = SortByVal(hashMap);

    for (int i = 0; i < vec.size(); i++){
        bool flag = true;
        while (flag){
            int j = s.find(vec[i].second);
            if (j >= 0){
                s.erase(s.begin() + j);
            }
            else{
                flag = false;
            }
        }
        
        if (vec[i].first != vec[i+1].first)
            break;
    }
    cout << s << endl;
    return 0;
}