poj--1306 Combinations(组合数)

题意

题解

#include <iostream>
#include <cstdio>
using namespace std;

typedef long long ll;
const int maxn = 100 + 10;

struct Solution{
ll  c[maxn][maxn];
int n, m;

void read(int _n, int _m){ n = _n, m = _m; }

Solution():n(0), m(0){ dp(); }

void dp(){
for(int i = 0; i < maxn; ++i) c[i][0] = 1;
for(int i = 1; i < maxn; ++i){
for(int j = 1; j < maxn; ++j)
c[i][j] = c[i - 1][j] + c[i - 1][j - 1];
}
}

void solve(){
printf("%d things taken %d at a time is %I64d exactly.\n", n, m, c
[m]);
}

};
int main()
{
int n, m;
Solution s;
while(cin >> n >> m && (n || m)){
s.read(n, m);
s.solve();
}
return 0;
}