POJ-2488-A Knight's Journey-DFS

题意：

给你一个， q*p 的棋盘，让你用马的走法，把所有点都走一遍，如果不行的话，输出impossible， 可以的话，按字典序小的路径的输出

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int flag[27][27];
int dx[]={-1,1,-2,2,-2,2,-1,1};
int dy[]={-2,-2,-1,-1,1,1,2,2};
int p, q,num;
struct node
{
    int x, y;
}ls[128];
void dfs(int x,int y)
{
    int i;
    if(num >= q*p)
        return ;
    for(i = 0; i < 8; i++)
    {
        int xx = x+dx[i];
        int yy = y+dy[i];
        if(xx>0 && xx<=q && yy>0 && yy<=p && !flag[xx][yy])
        {
            num++;
            ls[num].x = xx;
            ls[num].y = yy;
            flag[xx][yy] = 1;
            dfs(xx,yy);
            if(num >= p*q)
                return;
            flag[xx][yy] = 0;
            num--;
        }
    }
}
int main()
{
    int t,i;
    scanf("%d",&t);
    int io = 1;
    while(t--)
    {
        scanf("%d%d",&q,&p);
        num = 1;
        ls[1].x = 1;
        ls[1].y = 1;
        memset(flag,0,sizeof(flag));
        flag[1][1] = 1;
        dfs(1,1);
        printf("Scenario #%d:\n",io++);
        if(num == p*q)
        {
            for(i = 1; i <= p*q; i++)
            {
                printf("%c%d",ls[i].y+'A'-1,ls[i].x);
            }
            printf("\n");
        }
        else
            printf("impossible\n");
        printf("\n");
    }
    return 0;
}

讨论中神奇的写法，转下

92种棋盘，就13种可以，打表

#include <iostream>
using namespace std;


int main()
{
	freopen("in.txt","r",stdin);
	int i,n,p,q;
	cin>>n;
	for(i=1;i<=n;i++)
	{
		cin>>p>>q;
		cout<<"Scenario #"<<i<<":"<<endl;
		if(p==1 &&q ==1)
			cout<<"A1"<<endl;
		else if(p==3 && q==4)
			cout<<"A1C2A3B1D2B3C1A2C3D1B2D3"<<endl;
		else if(p==3 && q==7)
			cout<<"A1B3D2F1G3E2G1F3E1G2E3C2A3B1C3A2C1D3B2D1F2"<<endl;
		else if(p==3 && q==8)
			cout<<"A1B3C1A2C3D1B2D3E1G2E3C2A3B1D2F1H2F3G1E2G3H1F2H3"<<endl;
		else if(p==4 && q==3)
			cout<<"A1B3C1A2B4C2A3B1C3A4B2C4"<<endl;
		else if(p==4 && q==5)
			cout<<"A1B3C1A2B4D3E1C2D4E2C3A4B2D1E3C4A3B1D2E4"<<endl;
		else if(p==4 && q==6)
			cout<<"A1B3C1A2B4C2D4E2F4D3E1F3D2B1A3C4B2A4C3E4F2D1E3F1"<<endl;
		else if(p==5 && q==4)
			cout<<"A1B3A5C4D2B1A3B5D4C2B4A2C1D3C5A4B2D1C3D5"<<endl;
		else if(p==5 && q==5)
			cout<<"A1B3A5C4A3B1D2E4C5A4B2D1C3B5D4E2C1A2B4D5E3C2E1D3E5"<<endl;
		else if(p==6 && q==4)
			cout<<"A1B3A5C6D4B5D6C4D2B1A3C2B4A2C1D3B2D1C3D5B6A4C5A6"<<endl;
		else if(p==7 && q==3)
			cout<<"A1B3C1A2C3B1A3C2B4A6C7B5A7C6A5B7C5A4B2C4B6"<<endl;
		else if(p==7 && q==4)
			cout<<"A1B3A5B7D6B5A7C6D4C2A3B1D2C4B2A4B6D7C5A6C7D5B4D3C1A2C3D1"<<endl;
		else if(p==8 && q==3)
			cout<<"A1B3C1A2B4C2A3B1C3A4B2C4A5B7C5A6B8C6A7B5C7A8B6C8"<<endl;
		else
			cout<<"impossible"<<endl;
		cout<<endl;
	}
	return 0;

}