HDU 2111 Saving HDU

明显的贪心

#include <stdio.h>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
struct BaoBei{
    int p, m;
    double val;
};

bool cmp(const BaoBei &a, const BaoBei &b){    
    return a.p > b.p;　　　　// >号 降序排序
}
int main(){
    int v, n;
    vector<BaoBei> vec;
    while( cin >> v, v ){
        cin >> n;
        vec.clear();
        BaoBei tmp;
        for(int i = 0; i < n; ++i){
            cin >> tmp.p >> tmp.m;
            vec.push_back(tmp);
        }
        sort(vec.begin(), vec.end(), cmp);
        int ans = 0;
        for(int i = 0; i < n; ++i){
            if(v <= 0){
                break;
            } else {
                if( vec[i].m <= v ){
                    ans += vec[i].p * vec[i].m;
                    v -= vec[i].m;
                } else {
                    ans += v * vec[i].p;
                    v -= v;
                }
            }
        }
        cout << ans << endl;
    }
    return 0;
}