Submission #914029

#	Time	Username	Problem	Language	Result	Execution time	Memory
914029		VMaksimoski008	Regions (IOI09_regions)	C++17	95 / 100	8036 ms	101340 KiB

regions

#include <bits/stdc++.h>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()

using namespace std;
using pii = pair<int, int>;

const int maxn = 2e5 + 5;

int n, r, q, in[maxn], out[maxn], timer = 0, i, r1, r2, ans, lp, rp, mid;
short home[maxn];
vector<vector<int> > graph, dp;
vector<vector<pii> > by_home;

void dfs(int u) {
    in[u] = timer++;

    for(int &v : graph[u])
        dfs(v);

    out[u] = timer;
}

void dfs2(int u) {
    dp[home[u]][u]++;

    for(int &v : graph[u]) {
        dfs2(v);
        for(i=1; i<=r; i++)
            dp[i][u] += dp[i][v];
    }
}

int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> r >> q;
    graph.resize(n+1);
    by_home.resize(r+1);
    
    cin >> home[1];

    for(i=2; i<=n; i++) {
        int p;
        cin >> p >> home[i];
        graph[p].push_back(i);
    }

    if(r <= 500) {
        dp.resize(r+1, vector<int>(n+1));
        dfs2(1);

        vector<vector<int> > reg(n+1);
        for(i=1; i<=n; i++)
            reg[home[i]].push_back(i);

        while(q--) {
            ans=0;
            cin >> r1 >> r2;
    
            for(int &x : reg[r1])
                ans += dp[r2][x];
    
            cout << ans << '\n';
            cout.flush();
        }

        return 0;
    }

    dfs(1);

    for(i=1; i<=n; i++)
        by_home[home[i]].push_back({ in[i], out[i] });
    for(i=1; i<=r; i++)
        sort(all(by_home[i]));

    while(q--) {
        ans = 0;
        cin >> r1 >> r2;

        for(pii &u : by_home[r1]) {
            lp=0, rp=sz(by_home[r2])-1;
            int p1 = 1e9;

            while(lp <= rp) {
                mid = (lp + rp) / 2;
                if(by_home[r2][mid].first > u.first) p1 = mid, rp = mid - 1;
                else lp = mid + 1;
            }

            if(p1 == 1e9) continue;
            
            lp=p1, rp=sz(by_home[r2])-1;
            int p2 = 1e9;

            while(lp <= rp) {
                mid = (lp + rp) / 2;
                if(by_home[r2][mid].first < u.second) p2 = mid, lp = mid + 1;
                else rp = mid - 1;
            }

            if(p2 == 1e9) continue;

            ans += (p2 - p1 + 1);
        }

        cout << ans << endl;
    }
    
    return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 80 / 85