马的遍历（BFS

https://www.luogu.org/problemnew/show/P1443

模板BFS......

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<string>
#include<cmath>
#include<set>
#include<vector>
#include<stack>
#include<queue>
#include<map>
using namespace std;
#define ll long long
#define se second
#define fi first
const int INF= 0x3f3f3f3f;
const int N=1e5+5;

int n,m,a,b;
int dx[8]={2,2,1,1,-2,-2,-1,-1},dy[8]={1,-1,2,-2,1,-1,2,-2};
int step[405][405];
bool vis[405][405];

struct note
{
    int x,y;
    int s;
}w,p;

queue<note>q;

void bfs(int ax,int ay)
{
    w.x=ax; w.y=ay; w.s=0;
    vis[w.x][w.y]=1;
    step[w.x][w.y]=w.s;

    q.push(w);
    while( !q.empty())
    {
        p=q.front();
        q.pop();
        for(int i=0;i<8;i++)
        {
            w.x=p.x+dx[i];
            w.y=p.y+dy[i];
            if(w.x<=n&&w.x>=1&&w.y<=m&&w.y>=1&&vis[w.x][w.y]==0)
            {
                vis[w.x][w.y]=1;
                w.s=p.s+1;
                step[w.x][w.y]=w.s;
                q.push(w);
            }
        }
    }
}

int main()
{
    cin>>n>>m>>a>>b;
    memset(step,-1,sizeof(step));
    bfs(a,b);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++)
            printf("%-5d",step[i][j]);
        cout<<endl;
    }
}