Submission #578796

#	Time	Username	Problem	Language	Result	Execution time	Memory
578796		talant117408	Dynamic Diameter (CEOI19_diameter)	C++17	24 / 100	2476 ms	19032 KiB

diameter

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;

#define long                unsigned long 
#define pb                  push_back
#define mp                  make_pair
#define all(v)              (v).begin(),(v).end()
#define rall(v)             (v).rbegin(),(v).rend()
#define lb                  lower_bound
#define ub                  upper_bound
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'

const int N = 1e5+7;
set <pair <int, ll>> graph[N];
vector <pair <pii, ll>> edges;
ll df, vf;
int n, q;
ll w;

void find_furthest(int v, int p, ll dist = 0) {
    if (dist > df) {
        df = dist;
        vf = v;
    }
    for (auto to : graph[v]) {
        if (to.first == p) continue;
        find_furthest(to.first, v, dist+to.second);
    }
}

void subtask3() {
    for (auto to : edges) {
        if (to.first.first != 1) {
            return;
        }
    }
    set <pair <ll, int>> st;
    for (auto to : edges) {
        st.insert(mp(to.second, to.first.second));
    }
    ll last = 0;
    while (q--) {
        ll d, e;
        cin >> d >> e;
        d = (d + last) % (n - 1);
        e = (e + last) % w;
        auto &c = edges[d].second;
        auto b = edges[d].first.second;
        st.erase(mp(c, b));
        c = e;
        st.insert(mp(c, b));
        ll ans = 0;
        auto endit = st.begin();
        endit++; endit++;
        for (auto it = st.begin(); it != st.end() && it != endit; it++) {
            ans += (*it).first;
        }
        cout << ans << endl;
        last = ans;
    }
    exit(0);
}

void solve() {
    cin >> n >> q >> w;
    for (int i = 0; i < n-1; i++) {
        int a, b;
        ll c;
        cin >> a >> b >> c;
        if (a > b) swap(a, b);
        edges.pb(mp(mp(a, b), c));
        graph[a].insert(mp(b, c));
        graph[b].insert(mp(a, c));
    }
    
    subtask3();
    
    if (n <= 5000) {
        ll last = 0;
        while (q--) {
            ll d, e;
            cin >> d >> e;
            d = (d + last) % (n - 1);
            e = (e + last) % w;
            auto a = edges[d].first.first, b = edges[d].first.second;
            auto &c = edges[d].second;
            graph[a].erase(graph[a].find(mp(b, c)));
            graph[b].erase(graph[b].find(mp(a, c)));
            c = e;
            graph[a].insert(mp(b, c));
            graph[b].insert(mp(a, c));
            df = vf = 0;
            find_furthest(1, 1);
            df = 0;
            find_furthest(vf, vf);
            cout << df << endl;
            last = df;
        }
    }
}

int main() {
    do_not_disturb
    
    int t = 1;
    //~ cin >> t;
    while (t--) {
        solve();
    }
    
    return 0;
}
/*

*/

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