【POJ 1942】 Paths on a Grid

<span style="font-size:14px;">#include <iostream>
#include <cstdio>

using namespace std;

#define ll long long

int main()
{
    ll n,m,ans,i,t;

    while(~scanf("%lld %lld",&n,&m) && n || m)
    {
        if(m < n)
        {
            t = n;
            n = m;
            m = t;
        }
        ++m;
        ans = 1;
        for(i = 1; i <= n; ++i,++m)
        {
            ans = (ans*m)/i;
        }
        printf("%lld\n",ans);
    }

    return 0;
}
</span>