HDU 2111 Saving HDU

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

const int maxn = 1e5 + 10;
struct goods {
    int val;
    int wei;
}s[maxn];

bool cmp(const goods& a, const goods& b) {
    return a.val > b.val;
}

int main() {
    int v, n;
    while(~scanf("%d", &v)) {
        if(v == 0)
            break;
        scanf("%d", &n);
        for(int i = 1; i <= n; i ++)
            scanf("%d %d", &s[i].val, &s[i].wei);

        sort(s + 1, s + 1 + n, cmp);
        int out = 0;
        for(int i = 1; i <= n; i ++) {
            while(s[i].wei != 0 && v != 0) {
                out += s[i].val;
                v--;
                s[i].wei--;
            }
        }

        printf("%d\n", out);
    }

    return 0;
}