Submission #337342

#	Time	Username	Problem	Language	Result	Execution time	Memory
337342		arbor	Regions (IOI09_regions)	C++17	100 / 100	2929 ms	79332 KiB

regions

#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int MN = 2e5 + 5, MR = 2.5e4 + 5;
int N, R, Q, a[MN], sz[MN], tin[MN], tout[MN], tt;
int lb[MR], sub[MN], cnt1[450][MR], cnt2[MR][450];
vector<int> g[MN];
vector<pii> rg[MR];

void tour(int u) {
    tin[u] = ++tt;
    for (int v : g[u]) tour(v);
    tout[u] = tt;
    rg[a[u]].emplace_back(tin[u], tout[u]);
}

void go(int u, int r, int cnt) {
    cnt1[lb[r]][a[u]] += cnt;
    sub[u] = a[u] == r;
    for (int v : g[u]) {
        go(v, r, cnt + (a[v] == r));
        sub[u] += sub[v];
    }
    cnt2[a[u]][lb[r]] += sub[u];
}

int solve(int r1, int r2) {
    int p1 = 0, p2 = 0, ret = 0;
    stack<pii> st;
    while (p2 < rg[r2].size()) {
        if (p1 == rg[r1].size() || rg[r1][p1].first > rg[r2][p2].first) {
            while (!st.empty() && st.top().second < rg[r2][p2].first) st.pop();
            p2++;
            ret += st.size();
        } else if (rg[r1][p1].first < rg[r2][p2].first) {
            while (!st.empty() && st.top().second < rg[r1][p1].first) st.pop();
            st.push(rg[r1][p1]);
            p1++;
        }
    }
    return ret;
}

int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    cin >> N >> R >> Q >> a[1];
    int B = sqrt(N);
    for (int i = 2; i <= N; i++) {
        int p; cin >> p >> a[i];
        g[p].push_back(i);
        sz[a[i]]++;
    }
    tour(1);
    int id = 0;
    for (int i = 1; i <= R; i++) {
        if (sz[i] >= B) {
            lb[i] = ++id;
            go(1, i, a[1] == i);
        }
        sort(all(rg[i]));
    }
    for (int i = 0; i < Q; i++) {
        int r1, r2; cin >> r1 >> r2;
        if (sz[r1] >= B) cout << cnt1[lb[r1]][r2] << endl;
        else if (sz[r2] >= B) cout << cnt2[r1][lb[r2]] << endl;
        else cout << solve(r1, r2) << endl;
    }
    return 0;
}

Compilation message (stderr)

regions.cpp: In function 'int solve(int, int)':
regions.cpp:32:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |     while (p2 < rg[r2].size()) {
      |            ~~~^~~~~~~~~~~~~~~
regions.cpp:33:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |         if (p1 == rg[r1].size() || rg[r1][p1].first > rg[r2][p2].first) {
      |             ~~~^~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 85 / 85