HNU13033Football (贪心)

Your team played N matches during the first phase of the tournament, which has just finished. Only some teams, the ones with more accumulated points, will advance to the second phase of the tournament. However, as the main objective of the tournament is to
raise money, before the set of teams that will pass to the second phase is determined, each team is allowed to buy additional goals. These new goals count as normally scored goals, and may be used to alter the result of any of the matches the team played.

Your team‘s budget is enough to buy up to G goals. Can you tell the maximum total number of points your team can get after buying the goals, supposing the other teams will not buy any goals?

Sample input 1
2 1
1 1
1 1

Sample input 2
3 2
1 3
3 1
2 2

Sample input 3
4 10
1 1
2 2
1 3
0 4

Sample output 1
4

Sample output 2
6

Sample output 3
12

题意：给出N场比赛的每场比分s:r, s是本队得分，从开始手里有G个比分，可以分给每一场比分，赢了则加3个点，平局加1个点。输了得0个点。再问最多能得多少个点。

#include<stdio.h>
#include<algorithm>
#include<iostream>
using namespace std;
bool cmp(int a,int b){return a>b;}
int main()
{
    int sum,N,G,sub[100005],s,r,k,m,ss;
    while(scanf("%d%d",&N,&G)>0)
    {
        sum=0;k=0;m=0; ss=0;
        for(int i=0;i<N;i++)
        {
            scanf("%d%d",&s,&r);
           if(s-r<0) sub[k++]=s-r;
           else if(s-r==0)m++;
           else ss+=3;
        }

        sort(sub,sub+k,cmp);
        for(int j=0;j<=m&&j<=G;j++)
        {
            int s=m-j+j*3+ss,g=G-j;
            for(int i=0;i<k;i++)
            if(-sub[i]<g)
            {
                g+=sub[i]-1;s+=3;
            }
            else if(-sub[i]==g)
            g+=sub[i],s++;
            else break;
            if(s>sum)sum=s;
        }
        printf("%d\n",sum);
    }
}