求达捞优化

#include<bits/stdc++.h>
using namespace std;
int n,m,aa,bb;
int a[405][405];
int b[405][405];
void dfs(int x,int y,int tmp)
{
	if(b[x][y]==0)return;
	b[x][y]=0;
	if(a[x][y]<=tmp)return;
	a[x][y]=tmp;
	tmp++;
//	cout<<tmp;
	if(x>1&&y>2)dfs(x-1,y-2,tmp);
	if(x>2&&y>1)dfs(x-2,y-1,tmp);
	if(x<n&&y>2)dfs(x+1,y-2,tmp);
	if(x<n-1&&y>1)dfs(x+2,y-1,tmp);
	if(x>1&&y<m-1)dfs(x-1,y+2,tmp);
	if(x>2&&y<m)dfs(x-2,y+1,tmp);
	if(x<n&&y<m-1)dfs(x+1,y+2,tmp);
	if(x<n-1&&y<m)dfs(x+2,y+1,tmp);
	b[x][y]=1;
}
int main()
{
	for(int i=1;i<=405;i++)
	{
		for(int j=1;j<=405;j++)
		{
			a[i][j]=1000000;
			b[i][j]=1;
		}
	}
	cin>>n>>m>>aa>>bb;
	dfs(aa,bb,0);
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++)
		{
			if(a[i][j]==1000000)
				cout<<-1<<"    ";
			else
				cout<<a[i][j]<<"    ";
		}
		cout<<endl;
	}
	return 0;
}