Submission #1213912

#	Time	Username	Problem	Language	Result	Execution time	Memory
1213912		vanea	Regions (IOI09_regions)	C++20	100 / 100	2846 ms	31436 KiB

regions

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

const int mxN = 2e5+10;
const int mxR = 25010;

int reg[mxN];
vector<int>  adj[mxN], emp[mxR];
int tin[mxN], tout[mxN], timer = 0;
int idx[mxR], cntr = 0;
int precalc[500][mxR], tin_idx[mxN];

void dfs(int node, int p) {
    tin[node] = timer++;
    tin_idx[timer-1] = node;
    emp[reg[node]].push_back(tin[node]);
    for(auto it : adj[node]) {
        if(it == p) continue;
        dfs(it, node);
    }
    tout[node] = timer;
}

void dfs1(int node, int p, int cnt, int region) {
    if(reg[node] != region) precalc[idx[region]][reg[node]] += cnt;
    for(auto it : adj[node]) {
        if(it == p) continue;
        dfs1(it, node, cnt+(reg[node] == region), region);
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, r, q;
    cin >> n >> r >> q;
    cin >> reg[1];
    for(int i = 2; i <= n; i++) {
        int p;
        cin >> p >> reg[i];
        adj[p].push_back(i);
        adj[i].push_back(p);
    }
    dfs(1, 0);
    for(int i = 1; i <= r; i++) {
        if(emp[i].size() > 500) {
            idx[i] = cntr++;
            dfs1(1, 0, 0, i);
        }
    }
    while(q--) {
        int r1, r2;
        cin >> r1 >> r2;
        if(emp[r1].size() <= 500) {
            int ans = 0;
            for(auto it1 : emp[r1]) {
                int it = tin_idx[it1];
                int now = lower_bound(emp[r2].begin(), emp[r2].end(), tout[it]) -
                          lower_bound(emp[r2].begin(), emp[r2].end(), tin[it]);
                ans += now;
            }
            cout << ans << '\n';
            cout.flush();
        }
        else {
            cout << precalc[idx[r1]][r2] << '\n';
            cout.flush();
        }
    }
}

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