Submission #1326058

#	Time	Username	Problem	Language	Result	Execution time	Memory
1326058		nxk02102010	Dynamic Diameter (CEOI19_diameter)	C++20	49 / 100	4630 ms	46912 KiB

diameter

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

const int N = 200000 + 5;
const int MAX = 1000000;
const int MOD = 1000000007;
const long long oo = 1000000000000000005LL;

int n, q, m, TIME;
long long W, res;
long long lz[4 * N], d[N];
int in[N], out[N], ver[N], h[N];

vector<pair<int,int>> e[N];

struct ed {
    int u, v;
    long long w;
} edge[N];

void euler(int u, int p) {
    in[u] = ++m;
    out[u] = m;
    ver[m] = u;

    for (auto it : e[u]) {
        int v = it.first;
        int w = it.second;
        if (v == p) continue;
        h[v] = h[u] + 1;
        d[v] = d[u] + w;
        euler(v, u);
    }

    if (p != 0) {
        out[p] = ++m;
        ver[m] = p;
    }
}

struct node {
    long long du, dv, duw, dwv, duwv;
    node() {
        du = oo;
        dv = -oo;
        duw = -oo;
        dwv = -oo;
        duwv = 0;
    }
} st[4 * N];

void down(int id) {
    st[2 * id].du += lz[id];
    st[2 * id].dv += lz[id];
    st[2 * id].duw -= lz[id];
    st[2 * id].dwv -= lz[id];
    lz[2 * id] += lz[id];

    st[2 * id + 1].du += lz[id];
    st[2 * id + 1].dv += lz[id];
    st[2 * id + 1].duw -= lz[id];
    st[2 * id + 1].dwv -= lz[id];
    lz[2 * id + 1] += lz[id];

    lz[id] = 0;
}

long long minimize(const long long &A, const long long &B) {
    if (A < B) return A;
    return B;
}

long long maximize(const long long &A, const long long &B) {
    if (A > B) return A;
    return B;
}

node Merge(const node &A, const node &B) {
    node res;
    res.du = minimize(A.du, B.du);
    res.dv = maximize(A.dv, B.dv);

    res.duw = maximize(A.duw, B.duw);
    res.duw = maximize(res.duw, A.dv - 2 * B.du);

    res.dwv = maximize(A.dwv, B.dwv);
    res.dwv = maximize(res.dwv, B.dv - 2 * A.du);

    res.duwv = maximize(A.duwv, B.duwv);
    res.duwv = maximize(res.duwv, A.duw + B.dv);
    res.duwv = maximize(res.duwv, A.dv + B.dwv);

    return res;
}

void build(int id, int l, int r) {
    if (l == r) {
        st[id].du = d[ver[l]];
        st[id].dv = d[ver[l]];
        st[id].duw = -d[ver[l]];
        st[id].dwv = -d[ver[l]];
        return;
    }
    int mid = (l + r) / 2;
    build(2 * id, l, mid);
    build(2 * id + 1, mid + 1, r);
    st[id] = Merge(st[2 * id], st[2 * id + 1]);
}

void update(int id, int l, int r, int u, int v, long long x) {
    if (l > v || r < u) return;

    if (u <= l && r <= v) {
        st[id].du += x;
        st[id].dv += x;
        st[id].duw -= x;
        st[id].dwv -= x;
        lz[id] += x;
        return;
    }

    down(id);
    int mid = (l + r) / 2;
    update(2 * id, l, mid, u, v, x);
    update(2 * id + 1, mid + 1, r, u, v, x);
    st[id] = Merge(st[2 * id], st[2 * id + 1]);
}

void solve() {
    cin >> n >> q >> W;
    for (int i = 1; i <= n - 1; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        e[u].push_back({v, w});
        e[v].push_back({u, w});
        edge[i] = {u, v, w};
    }

    euler(1, 0);
    build(1, 1, m);

    while (q--) {
        int d_id;
        long long e_new;
        cin >> d_id >> e_new;

        d_id = (d_id + res) % (n - 1) + 1;
        e_new = (e_new + res) % W;

        int u = edge[d_id].u;
        int v = edge[d_id].v;
        long long w = edge[d_id].w;

        if (h[u] > h[v]) swap(u, v);

        update(1, 1, m, in[v], out[v], e_new - w);
        res = st[1].duwv;
        cout << res << "\n";

        edge[d_id].w = e_new;
    }
}

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

    int t = 1;
    while (t--) {
        solve();
    }
    return 0;
}

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