程式師世界 >> 編程語言 >> C語言 >> C++ >> C++入門知識 >> POJ 2488-A Knight&#39;s Journey£¨DFS£©

POJ 2488-A Knight&#39;s Journey£¨DFS£©

編輯：C++入門知識

POJ 2488-A Knight's Journey£¨DFS£©

A Knight's Journey Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 31702 Accepted: 10813

Description

Background
The knight is getting bZ†·Ÿ"http://www.Bkjia.com/kf/ware/vc/" target="_blank" class="keylink">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"pst">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 how 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

Sample Output

Scenario #1:
A1

Scenario #2:
impossible

Scenario #3:
A1B3C1A2B4C2A3B1C3A4B2C4

ÌâÒâ£º¹ú¼ÊÏóÆå£¬È»ºó¸øÒ»¸öÂí£¨Âí×ßÈÕ£© £¬¿ÉÒÔ´ÓÈÎÒâµã³ö·¢£¬ÕÒÒ»Ìõ¿ÉÒÔ·ÃÎÊËùÓÐ格×Ó£¨p*qµÄÆåÅÌ£©µÄÂ·¾¶£¬×¢ÒâÂ·¾¶Èç¹ûÓÐ¶àÌõÒªÇóÊä³ö×ÖµäÐò×îÐ¡µÄÄÇÌõ¡£¡£È»ºóÕâ¸ö¿ÉÒÔËÑË÷µÄÊ±ºò°´×ÖµäÐòËÑ¡£¡£¾ÍÊÇËÑË÷·½ÏòÒª¹Ì¶¨¡£¡£²»ÄÜËæÒâÐ´ÁË

È»ºóÆäËûµÄÃ»Ê²Ã´ÁË Ö±½ÓÉîËÑ£¬ËÑµ½´ð°¸Ö®ºóÖ±½Óreturn £»

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define ll long long
#define maxn 116
#define pp pair
#define INF 0x3f3f3f3f
#define max(x,y) ( ((x) > (y)) ? (x) : (y) )
#define min(x,y) ( ((x) > (y)) ? (y) : (x) )
using namespace std;
int n,m,k,ans,dir[8][2]={{-1,-2},{1,-2},{-2,-1},{2,-1},{-2,1},{2,1},{-1,2},{1,2}};
bool vis[27][27];
int sx[30],sy[30],top,ok;
void dfs(int x,int y)
{
	if(ok) return ;
	if(top==n*m)
	{
		ok=1;
		for(int i=0;i=1&&tx<=n&&ty>=1&&ty<=m&&!vis[tx][ty])
		{
			vis[tx][ty]=1;sx[top]=tx;sy[top++]=ty;
			dfs(tx,ty);
			vis[tx][ty]=0;top--;
		}
	}
}
int main()
{
	int T,cas=1;
	scanf("%d",&T);
    while(T--)
	{
		scanf("%d%d",&n,&m);ok=0;
		printf("Scenario #%d:\n",cas++);
		memset(vis,0,sizeof(vis));top=0;
		vis[1][1]=1;sx[top]=1;sy[top++]=1;
		dfs(1,1);
		if(!ok)
			printf("impossible");
		puts("");if(T)puts("");
	}
	return 0;
}