http://acm.hdu.edu.cn/showproblem.php?pid=2111

这个，我险些没有看懂题意= =。

原来给的单价是每个物品每个体积的价值，而不是每个物品的价值=w=。

#include <iostream>
#include <algorithm>
using namespace std;
#define N 105

struct treasure_node{
	int pi,mi;
};

treasure_node treasure[N];

bool cmp(treasure_node a,treasure_node b){
	return a.pi>b.pi;
}

int main(){
#ifndef ONLINE_JUDGE
	freopen("2111in.txt","r",stdin);
#endif
	int v,n,i,value;
	while (scanf("%d",&v)!=EOF&&v){
		scanf("%d",&n);
		for (i=0;i<n;i++)
			scanf("%d%d",&treasure[i].pi,&treasure[i].mi);
		sort(treasure,treasure+n,cmp);
		value=0;
		for (i=0;i<n&&v;i++){
			if (v>=treasure[i].mi){
				v-=treasure[i].mi;
				value+=treasure[i].mi*treasure[i].pi;
			}
			else {
				value+=treasure[i].pi*v;
				v=0;
			}
		}
		printf("%d\n",value);
	}
	return 0;
}