HDU 2510

DFS后打表

#include <iostream>
using namespace std;
int s[] ={0,0,0,4,6,0,0,12,40,0,0,171,410,0,0,1896,5160,0,0,32757,59984,0,0,431095,822229};
int main()
{
    int n;
    while(~scanf("%d",&n)&n)
    {
        printf("%d %d
",n,s[n]);                          
    }
}

#include <iostream>
using namespace std;
int s[25][25];
int a,b;
int n,cnt;
void dfs(int x)
{
    if(x==n+1)
    {
        int i,j;
        a=b=0;
        for(j=1;j<=n;j++) 
        if(s[1][j]) a++;
        else b++;
        for(int i=2;i<=n;i++)
        {
            for(j=1;j<=n-i+1;j++)
            {
                if(s[i-1][j]==s[i-1][j+1]) {
                    s[i][j]=1;
                    a++;
                } else {
                    s[i][j]=0;
                    b++;
                }
            }
        }
        if(a==b) cnt++;
        return;
    }
    s[1][x]=0;
    dfs(x+1);
    s[1][x]=1;
    dfs(x+1);
}
int main()
{
    for(n=1;n<=24;n++) 
    {
        cnt=0;
        dfs(1);
        printf("%d,",cnt);
    }
}