Submission #241847

#	Time	Username	Problem	Language	Result	Execution time	Memory
241847		thecodingwizard	Regions (IOI09_regions)	C++11	65 / 100	8077 ms	62104 KiB

regions

#include <bits/stdc++.h>

using namespace std;

#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>, 
             rb_tree_tag, tree_order_statistics_node_update>; 

int n, r, q; 
int R[200000];
vector<int> adj[200000];
vector<int> A[200001];
int start[200000], End[200000];
Tree<int> regions[200001];

int ctr = 0;
void dfs(int u) {
    start[u] = ctr;
    for (int v : adj[u]) {
        dfs(v);
    }
    End[u] = ctr++;
    regions[R[u]].insert(End[u]);
}

int main() {
    cin >> n >> r >> q;

    for (int i = 0; i < n; i++) {
        if (i == 0) {
            cin >> R[i];
        } else {
            int p;
            cin >> p >> R[i];
            adj[p-1].push_back(i);
        }
        A[R[i]].push_back(i);
    }

    dfs(0);

    map<pair<int, int>, long long> cache;
    for (int i = 0; i < q; i++) {
        int a, b; cin >> a >> b;
        if (cache.count(make_pair(a, b))) {
            cout << cache[make_pair(a, b)] << endl;
            continue;
        }
        bool swapped = false;
        if (A[a].size() > A[b].size()) {
            //swap(a, b);
            //swapped = true;
        }
        long long ans = 0;
        for (int n : A[a]) {
            int x = start[n], y = End[n];
            ans += regions[b].order_of_key(y) - regions[b].order_of_key(x);
        }
        cout << ans << endl;
        if (swapped) swap(a, b);
        cache[make_pair(a, b)] = ans;
    }

    return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 50 / 85