Submission #1307243

#	Time	Username	Problem	Language	Result	Execution time	Memory
1307243		buzdi	Regions (IOI09_regions)	C++17	55 / 100	8085 ms	27416 KiB

regions

#include <bits/stdc++.h>
#define ll long long

using namespace std;

const int NMAX = 2e5;
const int RMAX = 25000;
const int BLOCK = 160;

struct AIB {
    int n;
    int aib[NMAX + 1];

    void init(int n) {
        this->n = n;
        fill(aib + 1, aib + n + 1, 0);
    }

    void update(int pos, int value) {
        for(int i = pos; i <= n; i += i & (-i)) {
            aib[i] += value;
        }
    }

    int query(int pos) {
        int answer = 0;
        for(int i = pos; i >= 1; i -= i & (-i)) {
            answer += aib[i];
        }
        return answer;
    }
}aib;

int n, r, q, t;
int reg[NMAX + 1];
int freq[RMAX + 1];
int in[NMAX + 1], out[NMAX + 1];
vector<int> g[NMAX + 1], in_reg[RMAX + 1], nodes_reg[RMAX + 1];

void DFS(int node, int dad = 0) {
    in[node] = ++t;
    in_reg[reg[node]].push_back(in[node]);
    for(int next_node : g[node]) {
        if(next_node != dad) {
            DFS(next_node, node);
        }
    }
    out[node] = t;
}

int query_small(int r1, int r2) {
    int answer = 0;
    for(int node : nodes_reg[r1]) {
        auto itr = upper_bound(in_reg[r2].begin(), in_reg[r2].end(), out[node]);
        auto itl = lower_bound(in_reg[r2].begin(), in_reg[r2].end(), in[node]);
        answer += itr - itl;
    }
    return answer;
}

int query_big(int r1, int r2) {
    /// Activate r2
    /// Query r1

    aib.init(n);
    for(int node : nodes_reg[r2]) {
        aib.update(in[node], 1);
    }

    int answer = 0;
    for(int node : nodes_reg[r1]) {
        answer += aib.query(out[node]) - aib.query(in[node] - 1);
    }
    return answer;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> r >> q;
    cin >> reg[1];
    for(int i = 2; i <= n; i++) {
        int x;
        cin >> x >> reg[i];
        g[x].push_back(i);
        g[i].push_back(x);
    }

    for(int i = 1; i <= n; i++) {
        nodes_reg[reg[i]].push_back(i);
        freq[reg[i]]++;
    }
    DFS(1);

    while(q--) {
        int r1, r2;
        cin >> r1 >> r2;
        if(freq[r1] <= BLOCK) {
            cout << query_small(r1, r2) << endl;
        }
        else {
            cout << query_big(r1, r2) << endl;
        }
    }
    return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 40 / 85