Submission #597116

#	Time	Username	Problem	Language	Result	Execution time	Memory
597116		Valaki2	Dynamic Diameter (CEOI19_diameter)	C++14	24 / 100	5078 ms	12572 KiB

diameter

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

#define int long long
#define pb push_back

const int maxn = 1e5;

struct edge {
    int to, wei;
    edge() : to(0), wei(0) {}
    edge(int to_, int wei_) :
        to(to_), wei(wei_) {}
};

int n, q, w;
edge edges[2 * (maxn - 1)];
vector<edge* > g[maxn + 1];

void dfs(int cur, vector<bool> &vis, vector<int> &dist) {
    vis[cur] = true;
    for(edge* e : g[cur]) {
        if(!vis[e->to]) {
            dist[e->to] = dist[cur] + (e->wei);
            dfs(e->to, vis, dist);
        }
    }
}

int query() {
    int res = 0;
    vector<bool> vis(1 + n, false);
    vector<int> dist(1 + n, 0);
    dfs(1, vis, dist);
    int next_start = 1;
    for(int i = 1; i <= n; i++) {
        if(dist[i] > dist[next_start]) {
            next_start = i;
        }
    }
    vis.assign(1 + n, false);
    dist.assign(1 + n, 0);
    dfs(next_start, vis, dist);
    for(int i = 1; i <= n; i++) {
        res = max(res, dist[i]);
    }
    return res;
}

void solve() {
    cin >> n >> q >> w;
    for(int i = 0; i < n - 1; i++) {
        int idx_1 = 2 * i, idx_2 = 2 * i + 1;
        int a, b, c;
        cin >> a >> b >> c;
        edges[idx_1] = edge(b, c);
        edges[idx_2] = edge(a, c);
        g[a].pb(edges + idx_1);
        g[b].pb(edges + idx_2);
    }
    int last = 0;
    while(q--) {
        int d, e;
        cin >> d >> e;
        d = (d + last) % (n - 1);
        e = (e + last) % w;
        // ----- changable -----
        int idx_1 = 2 * d, idx_2 = 2 * d + 1;
        edges[idx_1].wei = e;
        edges[idx_2].wei = e;
        int result = query();
        // ----- changable -----
        cout << result << "\n";
        last = result;
    }
}

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