组合问题 ZOJ 1089 Lotto

组合问题

#include<iostream>
 using namespace std;
 int m;
 int n = 6;
int b[13];
int c[13];
void combination(int, int);

int main()
{
    int num;
    //freopen("test.txt","r", stdin);
    cin >> num;
    while (num)
    {
        for (int i = 0; i < num; i++)
        {
            cin >> c[i];
        }
        m = num;
        combination(0,0);
        cin >> num;
        if (num)
        cout << endl;
    }
    
    return 0;
}

//计算组合数
//m个里面取6个出来
void combination(int i, int current)
{
    if (i >= n)
    {
        for ( int j = 0; j < n; j++)
        {
            if (j == n-1)            
                cout << b[j];            
            else
            cout << b[j] << " ";    
        }
        cout << endl;
    }
    else
    {
        for (int j = current; j < m-n+i+1; j++)//这里j的上限做了优化，减小不必要的分枝
        {
            b[i] = c[j];
            combination(i+1, j+1);
        }
    }
}