hdu 1009贪心

水题，直接贴代码

/*
 * hdu1009/win.cpp
 * Created on: 2012-7-27
 * Author    : ben
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <functional>
#include <numeric>
#include <cctype>
using namespace std;
const int MAXN = 1005;
typedef struct Warehouse{
    double total;
    double need;
}Warehouse;
Warehouse wh[MAXN];
inline bool operator<(const Warehouse &wh1, const Warehouse &wh2) {
    return (wh1.total / wh1.need) > (wh2.total / wh2.need);
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    int N;
    double M, ans;
    while(scanf("%lf%d", &M, &N) == 2) {
        if(M == -1 && N == -1) {
            break;
        }
        for(int i = 0; i < N; i++) {
            scanf("%lf%lf", &wh[i].total, &wh[i].need);
        }
        sort(wh, wh + N);
        ans = 0;
        for(int i = 0; i < N; i++) {
            if(M <= 0) {
                break;
            }
            if(M >= wh[i].need) {
                ans += wh[i].total;
                M -= wh[i].need;
            }else {
                ans += M * wh[i].total / wh[i].need;
                M = 0;
            }
        }
        printf("%.3f\n", ans);
    }
    return 0;
}