pku2245 Lotto

#include<stdio.h>
#include<string.h>

const int N=13;
int n;
int base[N],map[N];
bool visit[N];

void dfs(int depth)
{
    if(depth==6)
    {
        for(int i=0;i<6;i++)
        {
            if(i) printf(" ");
            printf("%d",map[i]);
        }
        printf("\n");
        return;
    }

    for(int i=0;i<n;i++)
    {
        if(!visit[i]&&(depth==0||base[i]>map[depth-1]))
        {
            visit[i]=1;
            map[depth]=base[i];
            dfs(depth+1);
            visit[i]=0;
        }
    }
}

int main()
{
    bool first=true;
    while(scanf("%d",&n),n)
    {
        if(first) first=false;else printf("\n");

        for(int i=0;i<n;i++)
            scanf("%d",&base[i]);
        
        memset(visit,0,sizeof(visit));
        dfs(0);
    }
}

从流程可以看出，所谓的深度优先搜索，也就是在一个序列上从前向后依次枚举各个位置