标签:long 递推 int 数学 ret code style read i++
int n; unsigned long long a[550<<1]; int main(){ n=read(); a[0]=1; a[1]=1; for(rint i=2;i<=n+n;i++) a[i]=1ull*a[i-1]*i; unsigned long long ans=a[n+n]/a[n]/a[n]/(n+1); cout<<ans<<endl; return 0; }
标签:long 递推 int 数学 ret code style read i++
原文地址:https://www.cnblogs.com/Slager-Z/p/9901726.html