• 经典错误 2
• 结果：TLE + MLE

#include <iostream>
#include <cstring>
#include <queue>
using namespace std;
const int maxn=400+10;
int dx[]={-1,-2,-2,-1,1,2,2,1};
int dy[]={-2,-1,1,2,-2,-1,1,2};
int n,m;
int d[maxn][maxn];
void bfs(int x,int y){
	memset(d,0x3f,sizeof(d));
	queue<pair<int,int>>q;
	q.push({x,y});
	d[x][y]=0;
	int cnt=0;
	while(!q.empty()){
		int mx=q.front().first,my=q.front().second;
		q.pop();
		for(int i=0;i<8;i++){
			int nx=mx+dx[i],ny=my+dy[i];
			if(nx<1||nx>n||ny<1||ny>m)continue;
			d[nx][ny]=min(d[nx][ny],d[mx][my]+1);
			q.push({nx,ny});
		}
		cnt++;
		if(cnt>1000000){
			throw(114514);
		}
	}
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int x,y;
	cin>>n>>m>>x>>y;
	bfs(x,y);
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cout<<(d[i][j]==0x3f3f3f3f?-1:d[i][j])<<" ";
		}
		cout<<"\n";
	}
	return 0;
}

• 经典错误 1
• 结果：TLE + MLE

#include <bits/stdc++.h>
using namespace std;
const int maxn = 400 + 10 , maxm = 400 + 10;
int n , m , x , y;
int dis[maxn][maxm];
struct Node {int x , y;};
queue <Node> q;
int dx[8] = {-2 , -1 , -1 , -2 , 2 , 1 , 1 ,  2};
int dy[8] = {-1 , -2 , 2 ,  1 , 1 , 2 , -2 , -1};
void bfs (int x , int y) {
	for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) dis[i][j] = 999999;
	dis[x][y] = 0;
	q.push ({x , y});
	while (!q.empty ()) {
		Node u = q.front ();
		//cout << u.x << " " << u.y << "\n";
		q.pop ();
		for (int i = 0; i <= 8 - 1; i++) {
			int cx = u.x + dx[i] , cy = u.y + dy[i];
			//cout << cx << " " << cy << "\n";
			if (cx < 1 || cx > n || cy < 1 || cy > m) continue;
			if (dis[cx][cy] < dis[u.x][u.y] + 1) continue;
			dis[cx][cy] = dis[u.x][u.y] + 1;
			q.push ({cx , cy});
		}
	}
}
int main () {
	ios::sync_with_stdio (false);
	cin.tie (0) , cout.tie (0);
	cin >> n >> m >> x >> y;
	bfs (x , y);
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) cout << (dis[i][j] == 999999 ? -1 : dis[i][j])<< " ";
		cout << "\n";
	}
	return 0; 
}