Submission #781865

#	Time	Username	Problem	Language	Result	Execution time	Memory
781865		Andrey	Cat Exercise (JOI23_ho_t4)	C++14	100 / 100	294 ms	65136 KiB

Main

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

vector<long long> h(200001);
vector<long long> haha[200001];
vector<long long> dsu(200001);
vector<long long> dep(200001);
long long bruh[200001][19];

void dfs(long long a, long long t, long long d) {
    bruh[a][0] = t;
    dep[a] = d;
    for(long long v: haha[a]) {
        if(v != t) {
            dfs(v,a,d+1);
        }
    }
}

long long check(long long a) {
    long long c = a,d,e;
    while(dsu[c] != c) {
        c = dsu[c];
    }
    d = a;
    while(d != dsu[d]) {
        e = dsu[d];
        dsu[d] = c;
        d = e;
    }
    return c;
}

long long dist(long long a, long long b) {
    if(dep[a] < dep[b]) {
        swap(a,b);
    }
    long long c = dep[a]-dep[b],e = a,d = b;
    for(long long i = 0; i < 19; i++) {
        if((1 << i)&c) {
            e = bruh[e][i];
        }
    }
    if(b != e) {
        for(long long i = 18; i >= 0; i--) {
            if(bruh[e][i] != -1 && bruh[e][i] != bruh[b][i]) {
                e = bruh[e][i];
                b = bruh[b][i];
            }
        }
        e = bruh[e][0];
    }
    return dep[a]-dep[e]+dep[d]-dep[e];
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    for(long long i = 1; i <= 200000; i++) {
        dsu[i] = i;
    }
    long long n,a,b,y = 0;
    cin >> n;
    for(long long i = 1; i <= n; i++) {
        cin >> h[i];
    }
    vector<pair<long long,pair<long long,long long>>> edge(0);
    for(long long i = 0; i < n-1; i++) {
        cin >> a >> b;
        haha[a].push_back(b);
        haha[b].push_back(a);
        edge.push_back({max(h[a],h[b]),{a,b}});
    }
    sort(edge.begin(),edge.end());
    dfs(1,-1,0);
    for(long long i = 1; i < 19; i++) {
        for(long long j = 1; j <= n; j++) {
            if(bruh[j][i-1] != -1) {
                bruh[j][i] = bruh[bruh[j][i-1]][i-1];
            }
            else {
                bruh[j][i] = -1;
            }
        }
    }
    vector<long long> ans(n+1);
    for(long long i = 1; i <= n; i++) {
        while(y < n-1 && edge[y].first == i) {
            a = edge[y].second.first;
            b = edge[y].second.second;
            if(h[a] < h[b]) {
                swap(a,b);
            }
            b = check(b);
            dsu[b] = a;
            ans[a] = max(ans[a],dist(a,b)+ans[b]);
            y++;
        }
    }
    for(long long i = 1; i <= n; i++) {
        if(h[i] == n) {
            cout << ans[i];
        }
    }
    return 0;
}

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 23 / 23
• Subtask 7: 26 / 26