Submission #939714

#	Time	Username	Problem	Language	Result	Execution time	Memory
939714		ifateen	Regions (IOI09_regions)	C++14	100 / 100	5301 ms	45168 KiB

regions

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) (x).begin(), (x).end()
const int MAXN = 2e5 + 5, MAXSQRT = 501;
vector<int> adj[MAXN], comp[MAXN], region_in_times[MAXN];
int cmp[MAXN], in_time[MAXN], sub[MAXN], ans[MAXSQRT][25005], processed_index[MAXN], timer = 0;

void dfs(int u) {
    sub[u] = 1;
    in_time[u] = ++timer;
    region_in_times[cmp[u]].push_back(in_time[u]);
    for (auto &v: adj[u]) {
        dfs(v);
        sub[u] += sub[v];
    }
}

void pre_process(int u, int idx, int cnt) {
    if (cmp[u] == idx) cnt++;
    ans[processed_index[idx]][cmp[u]] += cnt;
    for (auto &v: adj[u]) pre_process(v, idx, cnt);
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, r, q;
    cin >> n >> r >> q;
    for (int i = 1; i <= n; i++) {
        if (i > 1) {
            int par;
            cin >> par;
            adj[par].push_back(i);
        }
        cin >> cmp[i];
        comp[cmp[i]].push_back(i);
    }
    dfs(1);
    timer = 0;
    int cnt = 0;
    for (int i = 1; i <= r; i++) {
        if (comp[i].size() <= MAXSQRT) continue;
        processed_index[i] = ++cnt;
        pre_process(1, i, 0);
    }
    while (q--) {
        int a, b;
        cin >> a >> b;
        if (processed_index[a]) cout << ans[processed_index[a]][b] << endl;
        else {
            int ret = 0;
            for (auto &u: comp[a])
                ret += lower_bound(all(region_in_times[b]), in_time[u] + sub[u]) -
                       lower_bound(all(region_in_times[b]), in_time[u]);
            cout << ret << endl;
        }
    }
}

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