Submission #424280

#	Time	Username	Problem	Language	Result	Execution time	Memory
424280		valerikk	Arboras (RMI20_arboras)	C++17	100 / 100	153 ms	23384 KiB

arboras

#include <bits/stdc++.h>

using namespace std;
#define int long long

const int N = 1e5 + 7;
const int md = 1e9 + 7;

int n, q;
int p[N], d[N];
vector<int> g[N];
int best[N], best2[N];
int dp[N], dp2[N];
int hld[N];
int sz[N];
int tin[N], tout[N];
int sum = 0;
int fen[N];
vector<int> ord;
int ind[2 * N];

void upd(int pos, int val) {
    int v = pos + n;
    ind[v] = val == 0 ? pos : -1;
    while (v > 1) {
        ind[v >> 1] = max(ind[v], ind[v ^ 1]);
        v >>= 1;
    }
}

int get_ind(int l, int r) {
    int vl = l + n, vr = r + n;
    int ret = -1;
    while (vl < vr) {
        if (vl & 1) ret = max(ret, ind[vl++]);
        if (vr & 1) ret = max(ret, ind[--vr]);
        vl >>= 1, vr >>= 1;
    }
    return ret;
}

void build() {
    for (int i = 0; i < n; ++i) ind[i + n] = i;
    for (int i = n - 1; i > 0; --i) ind[i] = max(ind[i << 1], ind[i << 1 | 1]);
}

bool is_par(int v, int u) {
    return tin[v] <= tin[u] && tout[v] >= tout[u];
}

int top(int v) {
    while (v != -1) {
        int i = get_ind(tin[hld[v]], tin[v] + 1);
        if (i != -1) return ord[i];
        v = p[hld[v]];
    }
    assert(0);
    return -1;
}

void add_fen(int pos, int val) {
    for (int i = pos + 1; i < N; i += i & -i) fen[i] += val;
}

void add_fen(int l, int r, int val) {
    sum += (r - l) * val;
    add_fen(l, val);
    add_fen(r, -val);
}

int get_fen(int r) {
    int res = 0;
    for (; r > 0; r -= r & -r) res += fen[r];
    return res;
}

void add_path(int v, int u, int val) {
    while (u != -1 && is_par(v, u)) {
        if (is_par(v, hld[u])) {
            add_fen(tin[hld[u]], tin[u] + 1, val);
        } else {
            add_fen(tin[v], tin[u] + 1, val);
        }
        u = p[hld[u]];
    }
}

int get_dp(int v) {
    return get_fen(tin[v] + 1);
}

void dfs(int v) {
    best[v] = best2[v] = -1;
    dp[v] = dp2[v] = 0;
    sz[v] = 1;
    for (int u : g[v]) {
        dfs(u);
        sz[v] += sz[u];
        if (dp[u] + d[u] > dp[v]) {
            dp2[v] = dp[v], best2[v] = best[v];
            dp[v] = dp[u] + d[u], best[v] = u;
        } else if (dp[u] + d[u] > dp2[v]) {
            dp2[v] = dp[u] + d[u];
            best2[v] = u;
        }
    }
    if (best[v] == -1 && !g[v].empty()) best[v] = g[v][0];
    if (best2[v] == -1 && g[v].size() >= 2) best2[v] = g[v][1];
    sum += dp2[v];
}

void dfs1(int v) {
    tin[v] = ord.size();
    ord.push_back(v);
    for (int &u : g[v]) {
        if (sz[u] > sz[g[v][0]]) swap(g[v][0], u);
    }
    for (int u : g[v]) {
        hld[u] = u == g[v][0] ? hld[v] : u;
        dfs1(u);
    }
    tout[v] = ord.size();
}

signed main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    p[0] = -1;
    for (int i = 1; i < n; ++i) {
        cin >> p[i];
        g[p[i]].push_back(i);
    }
    for (int i = 1; i < n; ++i) {
        cin >> d[i];
    }
    dfs(0);
    dfs1(0);
    for (int i = 0; i < n; ++i) add_path(i, i, dp[i]);
    build();
    for (int i = 1; i < n; ++i) {
        if (i == best[p[i]]) upd(tin[i], 1);
    }
    cout << sum % md << "\n";
    cin >> q;
    //int query_id = 0;
    while (q--) {
        int v, add;
        cin >> v >> add;
        d[v] += add;
        if (v == best[p[v]]) {
            add_path(top(v), p[v], add);
            /*cout << "query_id: " << query_id << endl;
            cout << "top: " << top(v) << endl;
            cout << "bottom: " << p[v] << endl;
            cout << "sum: " << sum << endl;*/
            v = top(v);
        }
        while (v != 0) {
            if (get_dp(v) + d[v] > get_dp(p[v])) {
                sum += get_dp(p[v]) - dp2[p[v]];
                dp2[p[v]] = get_dp(p[v]), best2[p[v]] = best[p[v]];
                upd(tin[best[p[v]]], 0);
                upd(tin[v], 1);
                best[p[v]] = v;
                add_path(top(p[v]), p[v], get_dp(v) + d[v] - get_dp(p[v]));
            } else {
                if (get_dp(v) + d[v] > dp2[p[v]]) {
                    sum += get_dp(v) + d[v] - dp2[p[v]];
                    dp2[p[v]] = get_dp(v) + d[v], best2[p[v]] = v;
                }
                break;
            }
            v = top(p[v]);
        }
        /*cout << "top: ";
        for (int i = 0; i < n; ++i) cout << top(i) << " ";
        cout << endl;
        cout << "best: ";
        for (int i = 0; i < n; ++i) cout << best[i] << " ";
        cout << endl;*/
        cout << sum % md << "\n";
        //++query_id;
    }
    return 0;
}

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 31 / 31
• Subtask 4: 45 / 45