Submission #996291

#	Time	Username	Problem	Language	Result	Execution time	Memory
996291		phoenix	Regions (IOI09_regions)	C++17	55 / 100	3911 ms	63556 KiB

regions

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int N = 200200;
const int R = 25025;
const int B = 1080;


int T;
int tin[N];
int tout[N];
vector<int> g[N];
int rg[N];

int m;
vector<int> heavy;
vector<int> ver[R];
vector<int> seg[R];

void precalc(int s) {
    tin[s] = ++T;
    seg[rg[s]].push_back(tin[s]);
    for (int to : g[s]) 
        precalc(to);
    tout[s] = ++T;
}


vector<vector<ll>> heavy_ans;
vector<ll> light_ans[N];

int lst[R];
int cnt[N];

bool isheavy(int r) {
    return ((int)seg[r].size() > B);
}

void dfs(int s) {
    for (int i = 0; i < m; i++) {
        int c = heavy[i];
        heavy_ans[i][c] += cnt[lst[c]];
    }

    int x = lst[rg[s]];
    cnt[s] = cnt[lst[rg[s]]] + 1;
    lst[rg[s]] = s;

    light_ans[s].resize(m);
    if (isheavy(rg[s])) {
        int c = lower_bound(heavy.begin(), heavy.end(), rg[s]) - heavy.begin();
        light_ans[s][c]++;
    }
    for (int to : g[s]) {
        dfs(to);
        for (int i = 0; i < m; i++)  
            light_ans[s][i] += light_ans[to][i];
    } 
    lst[rg[s]] = x;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, regions, q;
    cin >> n >> regions >> q;
    for (int i = 1; i <= n; i++) {
        int p;
        if (i > 1) {
            cin >> p;
            g[p].push_back(i);
        }
        cin >> rg[i];
        ver[rg[i]].push_back(i);
    }  
    
    precalc(1);

    for (int i = 1; i <= regions; i++) {
        if (isheavy(i)) {
            heavy.push_back(i);
            heavy_ans.push_back(vector<ll>(regions + 1));
            m++;
        }
        sort(seg[i].begin(), seg[i].end());
    }

    dfs(1);
    while (q--) {
        int r1, r2;
        cin >> r1 >> r2;
        int ans = 0;
        if (isheavy(r1)) {
            int c = lower_bound(heavy.begin(), heavy.end(), r1) - heavy.begin();
            ans = heavy_ans[c][r2];
        } else if (isheavy(r2)) { 
                int c = lower_bound(heavy.begin(), heavy.end(), r2) - heavy.begin();
                for (int v : ver[r1]) {
                    ans += light_ans[v][c];
                }
        } else {
            for (int v : ver[r1]) {
                int l, r;
                l = upper_bound(seg[r2].begin(), seg[r2].end(), tin[v]) - seg[r2].begin();
                r = upper_bound(seg[r2].begin(), seg[r2].end(), tout[v]) - seg[r2].begin();
                ans += max(r - l, 0);
            }
        }
        cout << ans << endl;
    }
}

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