50昏，求助

#include <iostream>
using namespace std;
int a[105][105];
int dp[105][105];
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
int ans=-114514;
int main(){
    int n,m;
    cin>>n>>m;
    for (int i = 1;i<=n;i++){
        for (int j = 1;j<=m;j++){
            cin>>a[i][j];
            dp[i][j]=1;
        }
    }
    for (int i = 1;i<=n;i++){
        for (int j = 1;j<=m;j++){
            for (int k = 0;k<4;k++){
                int nx=i+dx[k],ny=j+dy[k];
                if (a[nx][ny]>a[i][j]){
                    dp[nx][ny]=max(dp[i][j]+1,dp[nx][ny]);
                }
            }
        }
    }
    for (int i = 1;i<=n;i++){
        for (int j = 1;j<=m;j++){
            ans=max(dp[i][j],ans);
        }
    }
    cout<<ans<<endl;
    return 0;
}

思路是寻找最长距离之后枚举数组