实在看不出来哪会 RE。

大佬求调！QwQ

#include <bits/stdc++.h>
#define ll long long
#define pii pair <int, int>
using namespace std;
const int N = 1e3 + 10;
struct node {
	int x, y;
	int times;
} ;
queue <node> q;
bool vis[N][N];
int ans[N][N];
int n, m, a, b;
int dx[5] = {0, -1, 0, 0, 1};
int dy[5] = {0, 0, -1, 1, 0};
inline int bfs() {
	while (!q.empty()) {
		node t = q.front(); q.pop();
		int x = t.x, y = t.y, tim = t.times;
		for (int i = 1; i <= 4; ++i) {
			int nx = x + dx[i], ny = y + dy[i];
			if (!(nx >= 1 && nx <= n && ny >= 1 && ny <= m)) continue;
			if (vis[nx][ny]) continue;
			ans[nx][ny] = min(tim + 1, ans[nx][ny]);
			q.push({nx, ny, tim + 1});
			vis[nx][ny] = true;
		}
	}
}
int main() {
	cin >> n >> m >> a >> b;
	memset(ans, 0x3f, sizeof ans);
	for (int i = 1; i <= a; ++i) {
		int x, y; cin >> x >> y;
		q.push({x, y, 0});
		vis[x][y] = true;
		ans[x][y] = 0;
	}
	bfs();
	for (int i = 1; i <= b; ++i) {
		int x, y; cin >> x >> y;
		cout << ans[x][y] << "\n";
	}
	return 0;
}