OpenJudge Bailian 1088 滑雪 DFS

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#include <iomanip>
#include <math.h>
#include <map>
using namespace std;
#define FIN     freopen("input.txt","r",stdin);
#define FOUT    freopen("output.txt","w",stdout);
#define INF     0x3f3f3f3f
#define INFLL   0x3f3f3f3f3f3f3f
#define lson    l,m,rt<<1
#define rson    m+1,r,rt<<1|1
typedef long long LL;
typedef pair<int,int> PII;

const int MX = 1e2 + 5;

int mp[MX][MX];
int dp[MX][MX];
int n, m;
int to[4][2] = {1, 0, -1, 0, 0, 1, 0, -1};

bool check(int x, int y) {
    return x >= 1 && x <= n && y >= 1 && y <= m;
}

int dfs(int x, int y) {
    int ans = 0;
    if(dp[x][y])  return dp[x][y];
    for(int i = 0; i < 4; i++) {
        int xx = x + to[i][0];
        int yy = y + to[i][1];
        if(!check(xx, yy) || mp[xx][yy] >= mp[x][y])  continue;
        ans = max(ans, dfs(xx, yy));
    }
    dp[x][y] = ans + 1;
    return dp[x][y];
}

int main()
{
    //FIN
    while(cin >> n >> m) {
        for(int i = 1; i <= n; i++)
            for(int j = 1; j <= m; j++)
                cin >> mp[i][j];

        memset(dp, 0, sizeof(dp));

        int ans = 0;

        for(int i = 1; i <= n; i++) {
            for(int j = 1; j <= m; j++) {
                ans = max(ans, dfs(i, j));
            }
        }

//        for(int i = 1; i <= n; i++) {
//            for(int j = 1; j <= m; j++) {
//                printf("%4d", dp[i][j]);
//                if(j == m)  cout << endl;
//            }
//
//        }

        cout << ans << endl;
    }

    return 0;
}