RT，可能明天晚上才能回复及关注。

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

struct Pos{
    int x,y,step;
    Pos(int ax=0,int ay=0,int astep=0){
    	x=ax,y=ay,step=astep;
	} 
};

queue <Pos> q;

int n,m;
bool vis[402][402];
int a[402][402];

int go[9][2]={
	{0,0},
	{-1,-2},
	{-2,-1},
	{-2,1},
	{-1,2},
	{1,2},
	{2,1},
	{2,-1},
	{1,-2}
};

void bfs(){
    while(!q.empty()) {
        Pos now=q.front();
        q.pop();
        int x=now.x,y=now.y,step=now.step;
        a[x][y]=step;
        for(int i=1; i<=8; i++){
        	int x1=x+go[i][1],y1=y+go[i][2];
            if(x1>=1 && x1<=n && y1>=1 && y1<=m && !vis[x1][y1]){
                vis[x1][y1]=true;
                q.push(Pos(x1,y1,step+1));
            }
        }
    }
}

/*void out(int s){
	if(!s){
		cout<<"0    ";
		return ;
	}
	int w=5,q=s;
	while(q>0){w--,q/=10;}
	cout<<s;
	for(int i=1; i<=w; i++) cout<<" ";
}*/

int main(){
	int xx,yy;
    cin>>n>>m>>xx>>yy;
    q.push(Pos(xx,yy,0));
    bfs();
    for(int i=1; i<=n; i++){
        for(int j=1; j<=m; j++){
        	if(!vis[i][j]) printf("-1   ");
            else printf("%-5d",a[i][j]);
		}
        printf("\n");
    }
    return 0;
}