不喜欢状压只喜欢dfs的小萌新30分求助！！

#include<bits/stdc++.h>
using namespace std;
int ans,n,m;
int a[105][15],vis[105][15];
int max(int x,int y){return x > y ? x : y;}
void dfs(int x,int y,int num){
    if(x == n && y == m + 1)
    {
        ans = max(ans,num);
        return;
    }
    if(a[x][y] && !vis[x][y])
    {
        vis[x][y] = 1;
        vis[x + 1][y] = 1;
        vis[x + 2][y] = 1;
        vis[x - 1][y] = 1;
        vis[x - 2][y] = 1;
        vis[x][y + 1] = 1;
        vis[x][y + 2] = 1;
        vis[x][y - 1] = 1;
        vis[x][y - 2] = 1;
        if(y == m && x < n)
            dfs(x + 1,1,num + 1);
        else 
            dfs(x,y + 1,num + 1);
        vis[x][y] = 0;
        vis[x + 1][y] = 0;
        vis[x + 2][y] = 0;
        vis[x - 1][y] = 0;
        vis[x - 2][y] = 0;
        vis[x][y + 1] = 0;
        vis[x][y + 2] = 0;
        vis[x][y - 1] = 0;
        vis[x][y - 2] = 0;
    }
    else 
    {
        if(y == m && x < n)
            dfs(x + 1,1,num);
        else 
            dfs(x,y + 1,num);
    }
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i = 1;i <= n;i ++)
        for(int j = 1;j <= m;j ++)
        {
            char ch = getchar();
            while(ch != 'P' && ch != 'H')ch = getchar();
            if(ch == 'P')       a[i][j] = 1;
            if(ch == 'H')       a[i][j] = 0;
        }
    dfs(1,1,0);
    printf("%d\n",ans);
}