POJ 2243解题报告

BFS

#include <stdio.h>
#include <memory.h>
#include <stdlib.h>
const int maxn=15;
int visit[maxn*maxn];
int dir[8][2]={{-2,-1},{-2,1},{-1,2},{1,2},{2,1},{2,-1},{1,-2},{-1,-2}};
char a[3];
char b[3];
int bfs(int st,int fin);
int main()
{
	while(scanf("%s",a)!=EOF)
	{
		
		scanf("%s",b);
		int sy=a[0]-'a';
		int sx=a[1]-'1';
		int fy=b[0]-'a';
		int fx=b[1]-'1';
		memset(visit,0,sizeof(visit));
		int sl=sx*8+sy;
		int fl=fx*8+fy;
		if(sl==fl)
		{
			printf("To get from %s to %s takes 0 knight moves.\n",a,b);
		}
		else
		{
			printf("To get from %s to %s takes %d knight moves.\n",a,b,bfs(sl,fl));

		}
	}
	return 0;
}
int bfs(int st,int fin)
{
	int que[maxn*maxn];
	int font=0;
	int rear=0;
	int distance[maxn*maxn];
	distance[st]=0;
	que[rear++]=st;
	while(font<rear)
	{
		int on=que[font++];
		int x=on/8;
		int y=on%8;
		int i;
		for(i=0;i<8;i++)
		{
			int dx=x+dir[i][0];
			int dy=y+dir[i][1];
			int on2=dx*8+dy;
			if(dx>=0&&dx<8&&dy>=0&&dy<8&&!visit[on2])
			{
                 visit[on2]=1;
				 distance[on2]=distance[on]+1;
				 que[rear++]=on2;
				 if(on2==fin) return distance[on2];

			}

		}
     
	}
}