HDU 4221 Greedy?（贪心）

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<stdlib.h>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
using namespace std;
struct Work
{
    __int64 c,d;
};
Work work[100000+10];
int cmp(Work a,Work b)
{
    if(a.d==b.d)
    {
        return a.c<b.c;
    }
    return a.d<b.d;
}
int main()
{
    __int64 time ,ans;
    int cas=1;
    int t,n;
    int i,j,k;
    scanf("%d",&t);
    while(t--)
    {
        ans=0;time=0;
        scanf("%d",&n);
        for(i=0;i<n;i++)
        {
            scanf("%I64d%I64d",&work[i].c,&work[i].d);
        }
        sort(work,work+n,cmp);
        for(i=0;i<n;i++)
        {
            time+=work[i].c;
            if(time>work[i].d&&ans<time-work[i].d)
            {
                ans=time-work[i].d;
            }
        }
        printf("Case %d: %I64d\n",cas++,ans);
    }
    return 0;
}