Codeforces Round #279 (Div. 2)f

#include<iostream>
#include<string.h>
#include<stdio.h>
#include<algorithm>
#include<vector>
using namespace std;
const int maxa = 6006;
vector<int>e[maxa];
int d[maxa];
int a[maxa];
int mx, n;
void dfs(int q, int p){
    int k = lower_bound(d, d+n, a[q]) - d;
    mx = max(mx, k);
    int t = d[k];
    d[k] = a[q];
    for(int i = 0; i < e[q].size(); i++){
        if(e[q][i]!=p)
            dfs(e[q][i], q);
    }
    d[k] = t;
}
int main(){
    cin>>n;
    for(int i = 1; i <= n; i++)scanf("%d", a+i);
    for(int i = 1; i < n; i++){int x, y;
        scanf("%d%d", &x, &y);
        e[x].push_back(y);
        e[y].push_back(x);
    }
    for(int i =0; i <= n; i++)d[i] = (1<<30);
    for(int i = 1; i <= n; i++){
        dfs(i, 0);
    }printf("%d\n", mx+1);
}