暴力搜索怎么剪枝

#include<iostream>
#include<cstdio>
#define MAXN 2505
using namespace std;
int n,m,ans=0,ans1=0;
int map[MAXN][MAXN];
void dfs1(int x,int y)
{
    ans++;
    if(map[x+1][y+1]&&x+1>0&&x+1<=n&&y+1>0&&y+1<=m) dfs1(x+1,y+1);
}
void dfs2(int x,int y)
{
    ans1++;
    if(map[x+1][y-1]&&x+1>0&&x+1<=n&&y-1>0&&y-1<=m) dfs2(x+1,y-1);
}
    int main()
{
    int ans2=0;
         scanf("%d%d",&n,&m);
         for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
         scanf("%d",&map[i][j]);
         for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
            if(map[i][j]==1) 
            {
                ans=0;ans1=0;
                dfs1(i,j);dfs2(i,j);
                ans2=max(ans2,max(ans,ans1));    
            }
        cout<<ans2;
}