Submission #1067995

#	Time	Username	Problem	Language	Result	Execution time	Memory
1067995		vjudge1	Dynamic Diameter (CEOI19_diameter)	C++17	0 / 100	5061 ms	20892 KiB

diameter

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

const int N = 1e5 + 16;
int n, q, W, u, v;
ll w, result;
vector < pair <int, ll> > adj[N];
vector <int> id[N];

/*
4 3 2000
1 2 100
2 3 1000
2 4 1000
2 1030
1 1020
1 890
*/

/*
10 10 10000
1 9 1241
5 6 1630
10 5 1630
2 6 853
10 1 511
5 3 760
8 3 1076
4 10 1483
7 10 40
8 2051
5 6294
5 4168
7 1861
0 5244
6 5156
3 3001
8 5267
5 3102
8 3623
*/

ll a[N];
int h[N], par[N], sz[N], edge[N];
int chainHead[N], chainId[N], chainArr[N], pos[N], curPos = 1, curChain = 1;

void dfs(int k, int p) {
    sz[k] = 1;
    int i = -1;
    for (auto v : adj[k]) {
        i++;
        if (v.first == p) {
            continue;
        }
        edge[id[k][i]] = v.first;
        a[v.first] = v.second;
        h[v.first] = h[k] + 1;
        par[v.first] = k;
        dfs(v.first, k);
        sz[k] += sz[v.first];
    }
}

void hld(int k, int p) {
    if (!chainHead[curChain]) {
        chainHead[curChain] = k;
    }
    chainId[k] = curChain;
    pos[k] = curPos;
    chainArr[curPos] = k;
    curPos++;
    int heaviest = 0;
    for (auto v : adj[k]) {
        if (v.first == p) {
            continue;
        }
        if (heaviest == 0 || sz[v.first] > sz[heaviest]) {
            heaviest = v.first;
        }
    }
    if (heaviest) {
        hld(heaviest, k);
    }
    for (auto v : adj[k]) {
        if (v.first == p || v.first == heaviest) {
            continue;
        }
        curChain++;
        hld(v.first, k);
    }
}

int lca(int u, int v) {
    while (chainId[u] != chainId[v]) {
        if (chainId[u] > chainId[v]) {
            u = par[chainHead[chainId[u]]];
        }
        else {
            v = par[chainHead[chainId[v]]];
        }
    }
    if (h[u] < h[v]) {
        return u;
    }
    return v;
}

ll segmentTree[4 * N];

void build(int k, int l, int r) {
    if (l == r) {
        segmentTree[k] = a[chainArr[l]];
        return;
    }
    int mid = (l + r) / 2;
    build(2 * k, l, mid);
    build(2 * k + 1, mid + 1, r);
    segmentTree[k] = segmentTree[2 * k] + segmentTree[2 * k + 1];
}

void update(int k, int l, int r, int x, ll y) {
    if (l > x || x > r) {
        return;
    }
    if (l == r) {
        segmentTree[k] = y;
        return;
    }
    int mid = (l + r) / 2;
    update(2 * k, l, mid, x, y);
    update(2 * k + 1, mid + 1, r, x, y);
    segmentTree[k] = segmentTree[2 * k] + segmentTree[2 * k + 1];
}

ll get(int k, int l, int r, int x, int y) {
    if (l > y || x > r) {
        return 0;
    }
    if (l >= x && r <= y) {
        return segmentTree[k];
    }
    int mid = (l + r) / 2;
    return get(2 * k, l, mid, x, y) + get(2 * k + 1, mid + 1, r, x, y);
}

void updateTree(int id, ll val) {
    update(1, 1, curPos, pos[edge[id]], val);
}

ll getTree(int u, int v) {
    int LCA = lca(u, v);
    ll ans = 0;

    while (chainId[u] != chainId[LCA]) {
        ans = get(1, 1, curPos, pos[chainHead[chainId[u]]], pos[u]) + ans;
        u = par[chainHead[chainId[u]]];
    }

    while (chainId[v] != chainId[LCA]) {
        ans = get(1, 1, curPos, pos[chainHead[chainId[v]]], pos[v]) + ans;
        v = par[chainHead[chainId[v]]];
    }

    if (h[u] < h[v]) {
        ans = get(1, 1, curPos, pos[u] + 1, pos[v]) + ans;
    }
    else {
        ans = get(1, 1, curPos, pos[v] + 1, pos[u]) + ans;
    }
    return ans;
}

int parCd[N], szCd[N];
bool visited[N];

void countChild(int k, int p) {
    szCd[k] = 1;
    for (auto v : adj[k]) {
        if (visited[v.first] || v.first == p) {
            continue;
        }
        countChild(v.first, k);
        szCd[k] += szCd[v.first];
    }
}

int findCentroid(int k, int p, int treeSz) {
    for (auto v : adj[k]) {
        if (visited[v.first] || v.first == p) {
            continue;
        }
        if (sz[v.first] > treeSz / 2) {
            return findCentroid(v.first, k, treeSz);
        }
    }
    return k;
}

void cd(int k, int p) {
    countChild(k, k);
    int centroid = findCentroid(k, k, sz[k]);
    visited[centroid] = true;

    parCd[centroid] = p;

    for (auto v : adj[centroid]) {
        if (!visited[v.first]) {
            cd(v.first, centroid);
        }
    }
}

multiset < pair <ll, int> > s[N];

void updateCentroid(int k) {
    int v = k, p = k;
    while (v) {
        bool sameSub = false;
        for (auto x : s[v]) {
            if (x.second != p) {
                continue;
            }
            sameSub = true;
            ll dist = getTree(k, v);
            if (dist > x.first) {
                s[v].erase(x);
                s[v].insert({dist, p});
                break;
            }
        }
        if (!sameSub) {
            s[v].insert({getTree(k, v), p});
            if (s[v].size() > 2) {
                s[v].erase(s[v].begin());
            }
        }

        p = v;
        v = parCd[v];
    }
}

ll getCentroid(int k) {
    ll ans = 0;
    int v = k, p = k;
    while (v) {
        for (auto x : s[v]) {
            if (x.second != p) {
                ans = max(ans, x.first + getTree(k, v));
            }
        }
        p = v;
        v = parCd[v];
    }
    return ans;
}

pair <int, int> e[N];

void removeCentroid(int k) {
    int v = k, p = k;
    while (v) {
        pair <ll, int> val = {getTree(k, v), p};
        if (s[v].find(val) != s[v].end()) {
            s[v].erase(s[v].find(val));
        }
        p = v;
        v = parCd[v];
    }
}

void updateAll(int id, ll val) {
    u = e[id].first;
    v = e[id].second;

    removeCentroid(u);
    removeCentroid(v);
    updateTree(id, val);
    updateCentroid(u);
    updateCentroid(v);
}

int main() {
    ios_base :: sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

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

    dfs(1, 1);
    hld(1, 1);
    build(1, 1, curPos);

    cd(1, 0);

    for (int i = 1; i <= n; i++) {
        updateCentroid(i);
    }

    while (q--) {
        int d, f;
        cin >> d >> f;
        d = 1 + (d + result) % (n - 1);
        f = (f + result) % W;
        updateAll(d, f);

        result = 0;
        for (int i = 1; i <= n; i++) {
            result = max(result, getCentroid(i));
        }
        cout << result << "\n";
    }

    return 0;
}

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