Submission #501011

#	Time	Username	Problem	Language	Result	Execution time	Memory
501011		InternetPerson10	Dynamic Diameter (CEOI19_diameter)	C++17	24 / 100	5074 ms	15648 KiB

diameter

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

vector<vector<pair<int, ll>>> adj;
vector<pair<int, int>> pa;
vector<pair<int, ll>> dist;

void init(int n, int q, ll l, vector<int> u, vector<int> v, vector<ll> w) {
    pa.resize(n-1);
    adj.resize(n);
    for(int i = 0; i < n-1; i++) {
        u[i]--; v[i]--;
        pa[i] = {u[i], v[i]};
        adj[u[i]].push_back({v[i], w[i]});
        adj[v[i]].push_back({u[i], w[i]});
    }
    for(int i = 0; i < n; i++) sort(adj[i].begin(), adj[i].end());
    dist.resize(n);
}

void dfs(int n, ll dis = 0, int par = -1) {
    dist[n] = {dis, n};
    for(auto ch : adj[n]) {
        if(ch.first == par) continue;
        dfs(ch.first, dis + ch.second, n);
    }
}

ll get_diameter(int d, ll e) {
    int x, y;
    tie(x, y) = pa[d];
    int l = 0, r = adj[x].size();
    while(l != r-1) {
        int mid = (l+r)/2;
        if(adj[x][mid].first <= y) l = mid;
        else r = mid; 
    }
    adj[x][l].second = e;
    l = 0; r = adj[y].size();
    while(l != r-1) {
        int mid = (l+r)/2;
        if(adj[y][mid].first <= x) l = mid;
        else r = mid; 
    }
    adj[y][l].second = e;
    dfs(0);
    sort(dist.rbegin(), dist.rend());
    dfs(dist[0].second);
    sort(dist.rbegin(), dist.rend());
    return dist[0].first;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, q;
    ll l;
    cin >> n >> q >> l;
    vector<int> u(n-1), v(n-1);
    vector<ll> w(n-1);
    for(int i = 0; i < n-1; i++) {
        cin >> u[i] >> v[i] >> w[i];
    }
    init(n, q, l, u, v, w);
    ll last = 0;
    for(int i = 0; i < q; i++) {
        ll d, e;
        cin >> d >> e;
        d += last;
        d %= n-1;
        e += last;
        e %= l;
        last = get_diameter(d, e);
        cout << last << '\n';
    }
}

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 0 / 7
• Subtask 4: 0 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27