走迷宫【BFS】

>Link

ybtoj走迷宫

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>解题思路

一道非常典型的bfs

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>代码

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define N 2010
using namespace std;

const int xx[4] = {
    
    -1, 0, 0, 1}, yy[4] = {
    
    0, -1, 1, 0};
int n, a[N][N], sx, sy, tx, ty, qx[N], qy[N], head, tail, c[N][N];
bool v[N][N];
char cc;

int main()
{
    
    
	scanf ("%d", &n);
	for (int i = 1; i <= n; i++)
	  for (int j = 1; j <= n; j++)
	  {
    
    
	  	cc = getchar();
		while (cc != '0' && cc != '1') cc = getchar();
		a[i][j] = cc - '0';
	  }
	scanf ("%d%d%d%d", &sx, &sy, &tx, &ty);
	memset (c, 0x7f, sizeof (c));
	c[sx][sy] = 0, tail++, qx[1] = sx, qy[1] = sy, v[sx][sy] = 1;
	while (head < tail)
	{
    
    
		head++;
		int x = qx[head], y = qy[head];
		for (int i = 0; i < 4; i++)
		{
    
    
			int tox = x + xx[i], toy = y + yy[i];
			if (tox < 1 || toy < 1 || tox > n || toy > n) continue;
			if (a[tox][toy] == 1 || v[tox][toy]) continue;
			v[tox][toy] = 1;
			tail++;
			qx[tail] = tox, qy[tail] = toy;
			c[tox][toy] = c[x][y] + 1;
			if (tox == tx && toy == ty)
			{
    
    
				printf ("%d", c[tx][ty]);
				return 0;
			}
		}
	}
	return 0;
}