hdu 4504 威威猫系列故事——篮球梦

http://acm.hdu.edu.cn/showproblem.php?pid=4504

dp也可以  组合也可以

下面是组合代码：

#include<iostream>

#include<cmath>

#include<cstdio>

#include<string>

#include<cstring>

#include<vector>

#include<stack>

#include<queue>

#include<set>

#include<map>

#include<algorithm>



#define LL long long



using namespace std;



const int INF=0x3f3f3f3f;

const int MOD=100000;

const LL LMOD=100000;

const int N=105;

const int M=105;

const int K=6;

LL C(int n,int m)

{

    LL tmp=1;

    for(int i=n-m+1;i<=n;++i)

    {

        tmp=tmp*i;

        while(m>=1&&tmp%m==0)

        {

            tmp=tmp/m;

            --m;

        }

    }

    return tmp;

}

int main()

{

    //freopen("data.in","r",stdin);

    int T,A,B;

    while(scanf("%d %d %d",&A,&B,&T)!=EOF)

    {

       int need=(T/15/2+B-A);

       int n=(T/15+1)/2;

       LL sum=0;

       for(int i=0;i<=n;++i)

       for(int j=0;j<=n;++j)

       {

          if(i+j*2+(n-i-j)*3>need)

          {

             sum+=(C(n,i)*C(n-i,j));

          }

       }

       cout<<sum<<endl;

    }

    return 0;

}