Luo Gu P1434 [SHOI2002] skiing (dfs + memory search)

About Memory search: https://blog.csdn.net/hjf1201/article/details/78680814

Topic links: https://www.luogu.org/problem/P1434

Ideas: The results have been found over the points save up the next time required for search on this point, the direct use of stored results to return. Attention seeking is the longest path

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <queue>
#include <vector>
#include <cstring>
#include <map>
#define mem(a) memset(a,0,sizeof(a))
using namespace std;
typedef long long lll;
const int maxn = 200005;
const lll INF = 0x3f3f3f3f3f;
int dir[8][2]= {2,1,1,2,-2,1,-1,2,2,-1,1,-2,-2,-1,-1,-2};
int dir2[4][2]= {0,1,0,-1,1,0,-1,0};
bool flag;
int a[105][105],vis[105][105],ans,r,c;
int dfs(int x, int y){
  //  cout << x <<" "<<y <<" "<< cnt << endl;
   // vis[x][y] = 1;
    if(vis[x][y] != 0) return vis[x][y];
    int t ,tt = 1,i;
    for(i = 0; i < 4; i++)
    {
     int fx = x + dir2[i][0],fy = y + dir2[i][1];
     if(fx > 0 && fx < r+1 && fy > 0 && fy < c+1 && a[fx][fy] < a[x][y])
     {
         t = dfs(fx,fy) + 1;
         tt = max(t,tt);
     }
    }
    vis[x][y] = max(tt,vis[x][y]);
    return vis[x][y];
}
int main()
{

    cin >>r >> c;
    for(int i = 1; i <= r; i++)
    {
        for(int j = 1; j<= c; j++)
            cin >> a[i][j];
    }
    for(int i = 1; i <= r; i++)
    {
        for(int j = 1; j <= c; j++)
        {
            //cout << "==============" << endl;
            //cout << "i = "<< i<<" j = "<< j<< endl;
            vis[i][j] = dfs(i,j);;
            ans = max(ans,vis[i][j]);
           // cout << "==============" << endl;
        }
    }
    cout << ans << endl;
    return 0;
}