$$\color{red}{算法}\color{blue}{基础课}\color{purple}{笔记and题解}\color{green}{汇总}$$

考虑爆搜求出最优解。然后发现会超时，所以对每一个点记忆化它为起点的最优解，就可以直接过了。

#include <bits/stdc++.h>
using namespace std;
const int N = 315;
int n, m, f[N][N], h[N][N], ans;
const int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};

int dfs(int x, int y) {
    int &v = f[x][y];
    if (v != -1) return v;
    v = 1;
    for (int i = 0; i < 4; i++) {
        int xx = x + dx[i], yy = y + dy[i];
        if (xx > 0 && xx <= n && yy > 0 && yy <= m && h[x][y] > h[xx][yy]) v = max(v, dfs(xx, yy) + 1);
    }
    return v;
}
int main() {
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) scanf("%d", &h[i][j]), f[i][j] = -1;

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

    printf("%d\n", ans);
    return 0;
}