请问这个为啥MLE了呀？？？

#include<bits/stdc++.h>
#define ll long long
#define debug(x) cout<<"["<<x<<"]" <<endl;
#define mem(a,b) memset(a,b,sizeof(a));
#define f(x,y) for(int x=1;x<=y;x++)
using namespace std;
const int mx=110;
int mp[mx][mx],dp[mx][mx];
int r,c,res;
int f[4][2]={0,1,0,-1,1,0,-1,0};
bool check(int x,int y){
    if(x>=1&&x<=r&&y>=1&&y<=c)return true;
    else return false;
} 
bool bj(int x,int y){
    int flag=0;
    for(int i=0;i<4;i++){
        int xx=x+f[i][0];
        int yy=y+f[i][1];
        if(!check(xx,yy)||mp[xx][yy]>mp[x][y])continue;
        else flag=1;
    }
    if(flag==0)return true;
    else return false;
}
int dfs(int x,int y){
    if(dp[x][y]!=-1)return dp[x][y];
    //if(x)return 1;
    if(bj(x,y))return 1;
    for(int i=0;i<4;i++){
        int xx=x+f[i][0];
        int yy=y+f[i][1];
        if(!check(xx,yy)||mp[xx][yy]>mp[x][y])continue;
        else dp[x][y]=max(dp[x][y],dfs(xx,yy)+1);
    }
    return dp[x][y];
}
int main(){
    cin>>r>>c;
    f(i,r)f(j,c)cin>>mp[i][j];
    mem(dp,-1);
    f(i,r)f(j,c)res=max(res,dfs(i,j));
    cout<<res;
//  cout<<dfs(2,3);
    return 0;
}