Memory search-skiing

The link to the original question
is a very simple DP, the important thing is the process of
memoization.

Code

#include <bits/stdc++.h>
using namespace std;
const int N=310;
int n,m;
int g[N][N];
int f[N][N];
int dx[4]={
    
    -1,0,1,0},dy[4]={
    
    0,1,0,-1};
int dp(int i,int j)
{
    
    
    if(f[i][j]!=-1) return f[i][j];
    f[i][j]=1;
    for(int k=0;k<4;k++)
    {
    
    
        int x=i+dx[k],y=j+dy[k];
        if(x>=1&&x<=n&&y>=1&&y<=m&&g[x][y]<g[i][j])
            f[i][j]=max(f[i][j],dp(x,y)+1);
    }
    return f[i][j];
}
int main()
{
    
    
    cin>>n>>m;
    for(int i=1;i<=n;i++) 
        for(int j=1;j<=m;j++) 
            cin>>g[i][j];
    memset(f,-1,sizeof(f));
    int res=0;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            res=max(res,dp(i,j));
    cout<<res<<endl;
    return 0;
}