제출 #984994

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
984994		Br3ad	Regions (IOI09_regions)	C++17	30 / 100	7311 ms	131072 KiB

regions

#include <iostream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <numeric>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>

using namespace std;
#define ll long long
#define ull unsigned long long
#define f first
#define s second
#define PF push_front
#define PB push_back
#define MP make_pair
#define max(a, b) ((a > b)? a : b)
#define min(a, b) ((a < b)? a : b)
#define max3(a, b, c) max(max(a, b), c)
#define min3(a, b, c) min(min(a, b), c)

const int N = 2e5 + 5;
const int M = 1e9 + 7; 
const int inf = 0x3f3f3f3f;
const ll int INF = 1e18;

struct BIT {
    int sz;
    vector<int> tree;

    BIT(int n) : sz(n+1), tree(n+1, 0) {};

    void add(int pos, int val){
        for(; pos < sz; pos += pos&-pos) tree[pos] += val;
    }

    int sum(int pos){
        int ans = 0;
        for(; pos >= 1; pos -= pos&-pos) ans += tree[pos];
        return ans;
    }
};

vector<vector<int>> adj(N, vector<int>());
vector<int> to(N), tin(N), sz(N, 1);

int timer = 1;
void dfs(int cur, int prev){
    tin[cur] = timer++;
    for(int child : adj[cur]){
        if(child == prev) continue;
        dfs(child, cur);
        sz[cur] += sz[child];
    }
}

int main(){
    
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    
    // ifstream cin();
    // ofstream cout();
    
    int n, r, q, reg[N];
    cin >> n >> r >> q >> reg[1];

    vector<vector<int>> region(r+1, vector<int>());
    region[reg[1]].PB(1);

    for(int i = 2; i <= n; i++){
        cin >> to[i] >> reg[i];
        region[reg[i]].PB(i);
        adj[i].PB(to[i]);
        adj[to[i]].PB(i);
    }

    dfs(1, -1);

    vector<BIT> bit(r+1, BIT(n));

    // O(nlogn) pre-build fenwick tree
    for(int i = 1; i <= n; i++){
        bit[reg[i]].add(tin[i], 1);
        bit[reg[i]].add(tin[i] + sz[i], -1);
    }

    while(q--){
        int r1, r2;
        cin >> r1 >> r2;

        // O(max(r2)logn) = O(nlogn) query... too slow
        // Search for how many ancestor with region r above a person i can be achieved in O(logn)

        ll num = 0;
        for(int i : region[r2]){
            num += bit[r1].sum(tin[i]);
        }

        cout << num << endl;
    }

}

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