代码如下

#include <bits/stdc++.h>
using namespace std;

const int mx[4] = {0, 0, 1, -1};
const int my[4] = {1, -1, 0, 0};

int n, m;
int sx, sy, ex, ey;

int mv[500][500];
int mmap[500][500];

void bfs(pair<int, int> s) {
	queue<pair<int, int> > q;
	q.push(s);
	mv[s.first][s.second] = 0;
	while(!q.empty()) {
		int x = q.front().first, y = q.front().second, tx, ty, vv;
		q.pop();
		for(int i = 0; i < 4; ++i) {
			tx = mx[i] + x, ty = my[i] + y;
			if(tx < 0 || tx > n - 1 || ty < 0 || ty > n - 1)
				continue;
			vv = mv[x][y] + (mmap[x][y] ^ mmap[tx][ty]);
			//cout << x << " " << " " << y << " " << vv << endl;
			if(vv < mv[tx][ty]) {
				mv[tx][ty] = vv;
				q.push(make_pair(tx, ty));
			}
		}
	}
}

int main() {
	while(1) {
		memset(mv, 0x3f, sizeof(mv));
		memset(mmap, 0, sizeof(mmap));
		scanf("%d%d", &n, &m);
		if(n == 0 && m == 0)
			break;
		char ch[505];
		for(int i = 0; i < n; ++i) {
			scanf("%s", ch);
			for(int j = 0; j < m; ++j) {
				if(ch[j] == '#')
					mmap[i][j] = 1;
				else
					mmap[i][j] = 0;
			}
		}
		scanf("%d%d%d%d", &sx, &sy, &ex, &ey);
		bfs(make_pair(sx, sy));
		printf("%d\n", mv[ex][ey]);
	}
	return 0;
}

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谢谢各位大佬