UVA 7360 run step(组合数学)

#include<stdio.h> long long C(int a,int b){    long long ans=1;    for(int i=0;i<b;i++)    {        ans*=(a-i);        ans/=i+1;    }    return ans;}int main(){    int t;    int n;    int i,j,k,x,m;    scanf("%d",&t);    while(t--)    {        unsigned long long sum=0;        scanf("%d%d",&x,&n);        m=n/2;        int yi=0,er=m;    while(1)       {           if(yi>er) break;           if(er%2)           {               er--;               yi+=2;               continue;           }           int oo=er/2;           int jj=yi/2;           sum+=C((oo+jj),jj)*C((oo+jj),jj);           er--;           yi+=2;       }          printf("%d %lld",x,sum);    }    return 0;}