poj 2243 骑士游历问题 广度优先搜索

//=========================================================================
//
//>		  Author		:		flowertree
//>		  About			:		poj 2243
//>		  Time			:		2015.12.28
//>		  Algorithm		:		BFS 骑士游历问题 
//						:		在 8 * 8 方格中一点到一点 马的最少步数
//
//=========================================================================

#include <iostream>
#include <string.h>
#include <stdio.h>
#include <algorithm>
#include <queue>
using namespace std;

struct node
{
	int x;
	int y;
	int steps;
};

char start, ended;
int s, e;
int sx, sy, ex, ey;
int Move[8][2] = {-2, 1, -2, -1, -1, 2, -1, -2, 1, 2, 1, -2, 2, 1, 2, -1};		//马的八个方向
bool flag[9][9];

int BFS()		//广度优先搜索
{
	int tempx, tempy;
	queue<node> q;
	node t;
	t.x = sx;
	t.y = sy;
	t.steps = 0;
	flag[sx][sy] = true;
	q.push(t);
	while(!q.empty())
	{
		node temp = q.front();
		q.pop();
		for(int i = 0; i < 8; i++)
		{
			tempx = temp.x + Move[i][0];
			tempy = temp.y + Move[i][1];
			if(tempx < 1 || tempx > 8 || tempy > 8 || tempy < 1)
				continue;
			if(!flag[tempx][tempy] && (tempx == ex) && (tempy == ey))
				return temp.steps + 1;
			if(!flag[tempx][tempy])
			{
				flag[tempx][tempy] = true;
				node n;
				n.x = tempx;
				n.y = tempy;
				n.steps = temp.steps + 1;
				q.push(n);
			}
		}
	}
	return -1;
}

int main()
{
	while(scanf("%c%d %c%d", &start, &s, &ended, &e) != EOF)
	{
		getchar();
		memset(flag, false, sizeof(flag));
		sx = start - 'a' + 1;
		sy = s;
		ex = ended - 'a' + 1;
		ey = e;
		int temp;
		if((start == ended) && (s == e))
			temp = 0;
		else
			temp = BFS();
		printf("To get from %c%d to %c%d takes %d knight moves.\n", start, s, ended, e, temp);
	}
	system("pause");
	return 0;
}