https://www.luogu.org/problemnew/show/P1434
#include <bits/stdc++.h>
#define FF(a,b) for(int a=0;a<b;a++)
#define F(a,b) for(int a=1;a<=b;a++)
#define LEN 110
#define bug(x) cout<<#x<<"="<<x<<endl;
using namespace std;
int g[LEN][LEN];
int res[LEN][LEN];
int vis[LEN][LEN];
int N,M;
int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};
int valid(int i,int b){
if(i>=0 && i<b)
return 1;
return 0;
}
int dfs(int x,int y){
if(res[x][y]) return res[x][y];
int ans=0;
vis[x][y]=1;
FF(i,4){
int cx=x+dx[i];
int cy=y+dy[i];
if(valid(cx,N) && valid(cy,M) && (!vis[cx][cy]) && g[cx][cy]<g[x][y] )
ans=max(ans,dfs(cx,cy)+1);
}
vis[x][y]=0;
res[x][y]=ans;
return ans;
}
int main()
{
freopen("./in","r",stdin);
scanf("%d%d",&N,&M);
FF(i,N)FF(j,M)scanf("%d",&g[i][j]);
int ans=0;
FF(i,N)FF(j,M)ans=max(ans,dfs(i,j));
printf("%d",ans+1);
return 0;
}