B.选点

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 1e5 + 10;

int W[MAXN];
int L[MAXN],R[MAXN];
int Res[MAXN],dp[MAXN];
int pos = 0;

void Dfs(int x)
{
    if (x == 0)
        return;
    Res[++pos] = x;
    Dfs(R[x]);
    Dfs(L[x]);
}

int main()
{
    int n;
    cin >> n;
    for (int i = 1;i <= n;i++)
        cin >> W[i];
    for (int i = 1;i <= n;i++)
        cin >> L[i] >> R[i];
    Dfs(1);
    for (int i = 1;i <= n;i++)
        Res[i] = W[Res[i]];
    pos = 1;
    dp[1] = Res[1];
    for (int i = 2;i <= n;i++)
    {
        if (Res[i] > dp[pos])
        {
            dp[++pos] = Res[i];
        }
        else
        {
            int x = lower_bound(dp + 1, dp + 1 + pos, Res[i]) - dp;
            dp[x] = Res[i];
        }
    }
    cout << pos << endl;

    return 0;
}