Submission #1071837

#	Time	Username	Problem	Language	Result	Execution time	Memory
1071837		ArthuroWich	Regions (IOI09_regions)	C++17	45 / 100	8095 ms	29816 KiB

regions

#include <bits/stdc++.h>
using namespace std;
#define int long long int
vector<int> adj[300005], reg[25005];
int st[300005], en[300005], timer = 0;
void dfs(int i, int p) {
    st[i] = timer;
    timer++;
    for (int j : adj[i]) {
        if (j == p) {
            continue;
        }
        dfs(j, i);
    }
    en[i] = timer;
}
void solve() {
    int n, r, q;
    cin >> n >> r >> q;
    for (int i = 1; i <= n; i++) {
        int s, h;
        if (i == 1) {
            cin >> h;
            reg[h].push_back(i);
        } else {
            cin >> s >> h;
            reg[h].push_back(i);
            adj[s].push_back(i);
            adj[i].push_back(s);
        }
    }
    dfs(1, -1);
    while(q--) {
        int a, b, ans = 0;
        cin >> a >> b;
        for (int i : reg[a]) {
            for (int j : reg[b]) {
                if (st[i] < st[j] && st[j] < en[i]) {
                    ans++;
                }
            }
        }
        cout << ans << endl;
    }
}
int32_t main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    t = 1;
    while(t--) {
        solve();
    }
}

• Subtask 1: 15 / 15
• Subtask 2: 30 / 85