stable_sort()排序不改变相同值元素的顺序。

#include <bits/stdc++.h>
using namespace std;

bool cmp0(pair<string,int> a, pair<string, int> b)
{ //0为从高到低
        return a.second > b.second; 
}
bool cmp1(pair<string,int> a, pair<string, int> b)
{ //1从低到 高
        return a.second < b.second; 
}

int main()
{
    int n; cin>>n;
    int fs;cin>>fs;
    //建立名字成绩vector
    vector<pair<string,int>> V;
    for(int i = 0; i<n; i++)
    {
        string name; cin>>name;
        int score; cin>>score;
        V.push_back(make_pair(name,score));
    }
    //按成绩排序,0为从高到底
    if(fs == 0)
        stable_sort(V.begin(),V.end(),cmp0);
    if(fs == 1)  //1为从低到高
        stable_sort(V.begin(),V.end(),cmp1);
    //输出排序后的人名和成绩
    vector<pair<string,int>> ::iterator itr;
    for(itr = V.begin(); itr != V.end(); ++itr)
        cout<<(*itr).first<<' '<<(*itr).second<<endl;
    
    return 0;
}