Binomial Showdown
2008-05-03 00:10
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In how many ways can you choose k elements out of n elements, not taking order into account?
Write a program to compute this number.
Each test case consists of one line containing two integers n (n≥1) and k (0≤k≤n).
Input is terminated by two zeroes for n and k.
Warning: Don't underestimate the problem. The result will fit into an integer - but if all intermediate results arising during the computation will also fit into an integer depends on your algorithm. The test cases will go to the limit.
Source: University of Ulm Local Contest 1997
my c++ code:
#include <iostream>
using namespace std;
int main()
{
int n,m;
int i ;
int sum ;
while(scanf("%d %d",&n ,&m ) != EOF )
{
if(n ==0 && m==0 )
break;
if( m > n / 2 )
m = n - m;
double k = 1;
for(i = 1; i <= m ; i ++ )
k = k * ( n - m + i ) / i ; //* 1.0 ;
printf("%d/n", (long)k );
}
return 0;
}
Write a program to compute this number.
Input Specification
The input file will contain one or more test cases.Each test case consists of one line containing two integers n (n≥1) and k (0≤k≤n).
Input is terminated by two zeroes for n and k.
Output Specification
For each test case, print one line containing the required number. This number will always fit into an integer, i.e. it will be less than 231.Warning: Don't underestimate the problem. The result will fit into an integer - but if all intermediate results arising during the computation will also fit into an integer depends on your algorithm. The test cases will go to the limit.
Sample Input
4 2 10 5 49 6 0 0
Sample Output
6 252 13983816
Source: University of Ulm Local Contest 1997
my c++ code:
#include <iostream>
using namespace std;
int main()
{
int n,m;
int i ;
int sum ;
while(scanf("%d %d",&n ,&m ) != EOF )
{
if(n ==0 && m==0 )
break;
if( m > n / 2 )
m = n - m;
double k = 1;
for(i = 1; i <= m ; i ++ )
k = k * ( n - m + i ) / i ; //* 1.0 ;
printf("%d/n", (long)k );
}
return 0;
}
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