寒假训练 A - A Knight's Journey 搜索

Background

The knight is getting bored of seeing the same black and white squares again and again and has decided to make a journey

around the world. Whenever a knight moves, it is two squares in one direction and one square perpendicular to this. The world of a knight is the chessboard he is living on. Our knight lives on a chessboard that has a smaller area than a regular 8 * 8 board, but it is still rectangular. Can you help this adventurous knight to make travel plans?

Problem

Find a path such that the knight visits every square once. The knight can start and end on any square of the board.

Input

The input begins with a positive integer n in the first line. The following lines contain n test cases. Each test case consists of a single line with two positive integers p and q, such that 1 <= p * q <= 26. This represents a p * q chessboard, where p describes how many different square numbers 1, . . . , p exist, q describes h

dfs
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <algorithm>
using namespace std;
int p,q;
int flag=0;
bool vis[100][100];
int path[100][100];
int tx[8]={-1,1,-2,2,-2,2,-1,1};
int ty[8]={-2,-2,-1,-1,1,1,2,2};
bool judge(int x,int y)
{
    if(x>=1&&y>=1&&x<=p&&y<=q&&!flag&&!vis[x][y]) return true;
    return false;
}
void dfs(int x,int y,int step)//这里不知道你们有没有问题，反正我碰到了，就是，这里的x和y，与坐标系不一样
{
    path[step][0]=x;//x代表行
    path[step][1]=y;//y代表列
    if(step==p*q)//直角坐标系中x虽然是横轴，但是x的改变则是列的变化
    {
        flag=1;
        return ;
    }
    for(int i=0;i<8;i++)
    {
        int sx=x+tx[i];
        int sy=y+ty[i];
        if(judge(sx,sy))
        {
            vis[sx][sy]=1;
            dfs(sx,sy,step+1);
            vis[sx][sy]=0;
        }
    }
}
 
int main()
{
    int n,c=0;
    cin>>n;
    while(n--)
    {
        scanf("%d%d",&p,&q);
        printf("Scenario #%d:\n",++c);
        memset(vis,0,sizeof(vis));
        flag=0;
        vis[1][1]=1;
        dfs(1,1,1);
        if(flag==1)
        {
            for(int i=1;i<=p*q;i++)
            {
                printf("%c%d",path[i][1]-1+'A',path[i][0]);
            }
            printf("\n");
        }
        else printf("impossible\n");
        if(n!=0) printf("\n");
    }
    return 0;
}

　　

ow many different square letters exist. These are the first q letters of the Latin alphabet: A, . . .

Output

The output for every scenario begins with a line containing "Scenario #i:", where i is the number of the scenario starting at 1. Then print a single line containing the lexicographically first path that visits all squares of the chessboard with knight moves followed by an empty line. The path should be given on a single line by concatenating the names of the visited squares. Each square name consists of a capital letter followed by a number.
If no such path exist, you should output impossible on a single line.

Sample Input

3
1 1
2 3
4 3

Sample Output

Scenario #1:
A1
 
Scenario #2:
impossible
 
Scenario #3:
A1B3C1A2B4C2A3B1C3A4B2C4
 
题目大意：就是给你p行q列，求马是否可以走完，可以求出路径，不可以输出-1
意思很明确，不过毕竟是英文题，有点难读