Submission #578804

#	Time	Username	Problem	Language	Result	Execution time	Memory
578804		talant117408	Dynamic Diameter (CEOI19_diameter)	C++17	49 / 100	2404 ms	30880 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>, greater <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(st.find(mp(c, b)));
        c = e;
        st.insert(mp(c, b));
        ll ans = 0;
        ll cnt = 0;
        for (auto to : st) {
            ans += to.first;
            if (++cnt > 1) break;
        }
        cout << ans << endl;
        last = ans;
    }
    exit(0);
}

void subtask4() {
    vector <ll> ans_for(n+1);
    vector <pll> mx_child(n+1), dist_child(n+1);
    set <pair <ll, int>, greater <pair <ll, int>>> st;
    for (auto to : edges) {
        auto a = to.first.first;
        auto b = to.first.second;
        if (!(a*2 != b || a*2+1 != b)) {
            return;
        }
        if (a*2 == b) dist_child[a].first = to.second;
        else dist_child[a].second = to.second;
    }
    
    for (int i = 1; i <= n; i++) {
        if (sz(graph[i]) == 1) {
            int x = i;
            while (x) {
                if (x*2 <= n) mx_child[x].first = max(mx_child[x*2].first, mx_child[x*2].second)+dist_child[x].first;
                if (x*2+1 <= n) mx_child[x].second = max(mx_child[x*2+1].first, mx_child[x*2+1].second)+dist_child[x].second;
                x >>= 1;
            }
        }
    }
    for (int i = 1; i <= n; i++) {
        st.insert(mp(mx_child[i].first+mx_child[i].second, i));
    }
    
    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;
        int x = (b >> 1);
        if (a*2 == b) dist_child[a].first = e;
        else dist_child[a].second = e;
        while (x) {
            st.erase(st.find(mp(mx_child[x].first+mx_child[x].second, x)));
            if (x*2 <= n) mx_child[x].first = max(mx_child[x*2].first, mx_child[x*2].second)+dist_child[x].first;
            if (x*2+1 <= n) mx_child[x].second = max(mx_child[x*2+1].first, mx_child[x*2+1].second)+dist_child[x].second;
            st.insert(mp(mx_child[x].first+mx_child[x].second, x));
            x >>= 1;
        }
        cout << (*st.begin()).first << endl;
        last = (*st.begin()).first;
    }
    exit(0);
}

ll tree[N*4], lz[N*4];
int depth[N], timer;
pii range[N];
int parent[N];
int origin = 1;

void push(int v, int l, int r) {
    if (lz[v] != 0) {
        tree[v] += lz[v];
        if (l != r) {
            lz[v] += lz[v*2];
            lz[v] += lz[v*2+1];
        }
        lz[v] = 0;
    }
}

void update(int v, int l, int r, int ql, int qr, ll val) {
    push(v, l, r);
    if (ql > r || l > qr) return;
    if (ql <= l && r <= qr) {
        lz[v] += val;
        push(v, l, r);
        return;
    }
    int mid = (l+r) >> 1;
    update(v*2, l, mid, ql, qr, val);
    update(v*2+1, mid+1, r, ql, qr, val);
    tree[v] = max(tree[v*2], tree[v*2+1]);
}

ll get(int v, int l, int r, int ql, int qr) {
    push(v, l, r);
    if (ql > r || l > qr) return -9e18;
    if (ql <= l && r <= qr) return tree[v];
    int mid = (l+r) >> 1;
    return max(get(v*2, l, mid, ql, qr), get(v*2+1, mid+1, r, ql, qr));
}

void dfs(int v = 1, int p = 1, ll dist = 0) {
    range[v].first = ++timer;
    update(1, 1, n, timer, timer, dist);
    parent[v] = origin;
    for (auto to : graph[v]) {
        if (to.first == p) continue;
        depth[to.first] = depth[v] + 1;
        if (v == 1) origin = to.first;
        dfs(to.first, v, dist+to.second);
    }
    range[v].second = timer;
}

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));
    }
    
    
    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;
        }
        return;
    }
    subtask3();
    subtask4();
    
    dfs();
    set <pair <ll, int>, greater <pair <ll, int>>> st;
    for (auto to : graph[1]) {
        st.insert(mp(get(1, 1, n, range[to.first].first, range[to.first].second), to.first));
    }
    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;
        if (depth[a] < depth[b]) swap(a, b);
        st.erase(st.find(mp(get(1, 1, n, range[parent[b]].first, range[parent[b]].second), parent[b])));
        update(1, 1, n, range[b].first, range[b].second, e-c);
        c = e;
        st.insert(mp(get(1, 1, n, range[parent[b]].first, range[parent[b]].second), parent[b]));
        auto res = (*st.begin()).first;
        cout << res << endl;
        last = res;
    }
}

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: 7 / 7
• Subtask 4: 18 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27