10105 - Polynomial Coefficients

描述：杨辉三角与二项式定理
#include <cstdio>
int solve(int n,int m)
{
    int sum=1;
    for(int i=n; i>m; --i) sum*=i;
    for(int i=2; i<=n-m; ++i) sum/=i;
    return sum;
}
int main()
{
    //freopen("a.txt","r",stdin);
    int n,m,sum,k;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        sum=1;
        for(int i=0; i<m; i++)
        {
            scanf("%d",&k);
            if(k)
            {
                sum*=solve(n,k);
                n-=k;
            }
        }
        printf("%d\n",sum);
    }
    return 0;
}