Submission #1245176

#	Time	Username	Problem	Language	Result	Execution time	Memory
1245176		Mousa_Aboubaker	Dynamic Diameter (CEOI19_diameter)	C++20	31 / 100	280 ms	25988 KiB

diameter

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

template <typename T>
using pqg = priority_queue<T, vector<T>, greater<T>>;

struct LazySegmentTree
{
    int n;
    vector<long long> seg;
    vector<long long> lazy;
    void push(int v)
    {
        lazy[v * 2] += lazy[v];
        lazy[v * 2 + 1] += lazy[v];
        seg[v * 2] += lazy[v];
        seg[v * 2 + 1] += lazy[v];
        lazy[v] = 0;
    }
    LazySegmentTree(int _n)
    {
        n = _n;
        seg.assign(n * 4, 0);
        lazy.assign(n * 4, 0);
    }
    void update(int l, int r, long long val, int tl, int tr, int v)
    {
        if (r < tl or tr < l)
            return;
        if (l <= tl and tr <= r)
        {
            seg[v] += val;
            lazy[v] += val;
            return;
        }
        push(v);
        int md = (tl + tr) / 2;
        update(l, r, val, tl, md, v * 2);
        update(l, r, val, md + 1, tr, v * 2 + 1);
        seg[v] = max(seg[v * 2], seg[v * 2 + 1]);
    }
    void update(int l, int r, long long val)
    {
        update(l, r, val, 0, n - 1, 1);
    }
    long long query(int l, int r, int tl, int tr, int v)
    {
        if (r < tl or tr < l)
            return 0;
        if (l <= tl and tr <= r)
            return seg[v];
        push(v);
        int md = (tl + tr) / 2;
        return max(query(l, r, tl, md, v * 2), query(l, r, md + 1, tr, v * 2 + 1));
    }
    long long query(int l, int r)
    {
        return query(l, r, 0, n - 1, 1);
    }
};

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, q;
    long long w;
    cin >> n >> q >> w;
    vector<tuple<int, int, long long>> edges(n);
    for (int i = 1; i < n; i++)
    {
        auto &[u, v, c] = edges[i];
        cin >> u >> v >> c;
        if (u > v)
            swap(u, v);
    }

    vector adj(n + 1, vector<pair<int, long long>>());
    for (int i = 1; i < n; i++)
    {
        auto [u, v, c] = edges[i];
        adj[u].push_back({v, c});
        adj[v].push_back({u, c});
    }
    vector<int> in(n + 1), out(n + 1), par(n + 1), euler(n);
    vector<long long> sum(n + 1);
    LazySegmentTree seg(n);
    int timer = 0;
    auto dfs = [&](auto self, int u, int p, int pp) -> void
    {
        par[u] = pp;
        euler[timer] = u;
        in[u] = timer++;
        for (auto [v, c] : adj[u])
        {
            if (v == p)
                continue;
            bool can = pp == -1;
            if (can)
                pp = v;
            self(self, v, u, pp);
            if (can)
                pp = -1;
        }
        out[u] = timer;
    };
    dfs(dfs, 1, -1, -1);
    for (int i = 1; i < n; i++)
    {
        auto &[u, v, c] = edges[i];
        if (in[u] > in[v])
            swap(u, v);
        seg.update(in[v], out[v] - 1, c);
    }
    multiset<long long> st;
    st.insert(0);
    for (auto [v, c] : adj[1])
    {
        st.insert(seg.query(in[v], out[v] - 1));
    }

    long long lst = 0;
    while (q--)
    {
        int d;
        long long e;
        cin >> d >> e;
        d = (d + lst) % (n - 1) + 1;
        e = (e + lst) % w;
        auto &[u, vv, c] = edges[d];
        long long bef = c;
        c = e;
        st.erase(st.find(seg.query(in[par[vv]], out[par[vv]] - 1)));
        // for(auto [v, c]: adj[1])
        // {
        //     cout << v << ' ' << seg.query(in[v], out[v] - 1) << '\n';
        // }
        // cout << "\n\n";
        seg.update(in[vv], out[vv] - 1, c - bef);
        // for(auto [v, c]: adj[1])
        // {
        //     cout << v << ' ' << seg.query(in[v], out[v] - 1) << '\n';
        // }
        st.insert(seg.query(in[par[vv]], out[par[vv]] - 1));
        long long res = *prev(st.end()) + *prev(prev(st.end()));
        cout << res << '\n';
        lst = res;
    }
}

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