Solution UVa-Uhunt: 530 - Binomial Showdown

 Problem: http://uva.onlinejudge.org/external/5/530.pdf

Last Submissions
Problem	Verdict	Lang	Time	Best	Rank	Submit Time
| discuss530 - Binomial Showdown	Accepted	C++11	0.000	0.000	3421	2 mins ago

Solution: (time AC: 0s)

#include<bits/stdc++.h>

#define int long long

using namespace std;

unordered_map<string, int> F;

string C(int n, int k){

    return to_string(n)+" "+to_string(k);

}

int f(int n, int k){

    if (F.count(C(n,k))) return F[C(n,k)];

    if (k==1) return n;

    if (k==n || k==0) return 1;

   

    int C_k1_n1= f(n-1, k-1);

    int C_k_n1= C_k1_n1 * (n-k) *1.0/ k;    //2f -> 1f

    return  F[C(n,k)]= C_k1_n1 + C_k_n1;

    //return F[n][k]= f(n-1, k-1) + f(n-1, k);

}

int32_t main(){

    ios_base::sync_with_stdio(0);

    int n, k;

    while(cin >> n >> k && (n || k)){

        k= min(k, n-k);

        cout<<f(n,k)<<"\n";

    }

}