Submission #1239455

#	Time	Username	Problem	Language	Result	Execution time	Memory
1239455		phungha	Regions (IOI09_regions)	C++20	0 / 100	4 ms	5808 KiB

regions

#include <bits/stdc++.h>
using namespace std;

int n, r, q, h[200001], timer = 0, tin[200001], tout[200001], tin_node[200001];
int region_id[25001], cnt[159][25001];
vector<int> child[200001], region[25001];

void dfs(int u) {
    tin[u] = ++timer;
    tin_node[tin[u]] = u;
    region[h[u]].push_back(tin[u]);
    for (int v: child[u])
        dfs(v);
    tout[u] = timer;
}

void dfs2(int u, int parent_region, int parent_cnt) {
    if (h[u] == parent_region) parent_cnt++;
    cnt[region_id[parent_region]][h[u]] += parent_cnt;
    for (int v: child[u])
        dfs2(v, parent_region, parent_cnt);
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    freopen("test33.in", "r", stdin);
    freopen("test.out", "w", stdout);
    cin >> n >> r >> q;
    cin >> h[1];
    for (int i = 2; i <= n; i++) {
        int si;
        cin >> si >> h[i];
        child[si].push_back(i);
    }
    dfs(1);
    int block = sqrt(n), current_id = 0;
    for (int i = 1; i <= r; i++)
        if (region[i].size() >= block) {
            region_id[i] = ++current_id;
            dfs2(1, i, 0);
        }
    while (q--) {
        int r1, r2;
        cin >> r1 >> r2;
        if (region[r1].size() >= block)
            cout << cnt[region_id[r1]][r2] << "\n";
        else {
            int ans = 0;
            for (int u: region[r1])
                ans += upper_bound(region[r2].begin(), region[r2].end(), tout[tin_node[u]]) -
                       lower_bound(region[r2].begin(), region[r2].end(), tin[tin_node[u]]);
            cout << ans << "\n";
        }
    }
    return 0;
}

Compilation message (stderr)

regions.cpp: In function 'int main()':
regions.cpp:26:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     freopen("test33.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen("test.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 15
• Subtask 2: 0 / 85