Submission #569748

#	Time	Username	Problem	Language	Result	Execution time	Memory
569748		erto	Regions (IOI09_regions)	C++17	90 / 100	8054 ms	62456 KiB

regions

#include <bits/stdc++.h>
typedef long long int ll;
#define INF (1e9 + 7)
#define INF2 (998244353)
#define N (ll)2e5 + 5
using namespace std;
//#define int ll

int n, g, h, t1, t2, cur = 1, q, R;

int d[N], st[N], en[N], par[N][20], r[N];

vector<int> v[N], sts[N], ens[N], r2[N];

void dfs(int x, int p){
    st[x] = cur++;
    sts[r[x]].push_back(cur - 1);
    r2[r[x]].push_back(x);

    par[x][0] = p;
    for(int i = 1; i<=20; i++){
        par[x][i] = par[par[x][i - 1]][i - 1];
    }

    for(auto u : v[x]){
        if(u != p)dfs(u, x);
    }
    en[x] = cur++;
    ens[r[x]].push_back(cur - 1);
}

void solve(){
    cin >> n >> R >> q;
    cin >> r[1];

    for(int i=2; i<=n; i++){
        cin >> g >> r[i];
        v[g].push_back(i);
    }
    dfs(1, 0);

    for(int i=1; i<=q; i++){
        cin >> g >> h;
        if(sts[g].size() > sts[h].size()){
            int sum=0;
            for(auto u : r2[h]){
                t1 = lower_bound(sts[g].begin(), sts[g].end(), st[u]) - sts[g].begin();
                t2 = lower_bound(ens[g].begin(), ens[g].end(), st[u]) - ens[g].begin();
                sum += t1 - t2;
            }
            cout << sum << endl;
        }
        else{
            int sum=0;
            for(auto u : r2[g]){
                t1 = lower_bound(ens[h].begin(), ens[h].end(), st[u]) - ens[h].begin();
                t2 = lower_bound(ens[h].begin(), ens[h].end(), en[u]) - ens[h].begin();
                sum += t2 - t1;
            }
            cout << sum << endl;
        }
    }
}   



signed main(){ 
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
    //cin>>T;
    while (T--){
        solve();
    }
}

Compilation message (stderr)

regions.cpp: In function 'void dfs(int, int)':
regions.cpp:22:19: warning: iteration 19 invokes undefined behavior [-Waggressive-loop-optimizations]
   22 |         par[x][i] = par[par[x][i - 1]][i - 1];
      |         ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
regions.cpp:21:21: note: within this loop
   21 |     for(int i = 1; i<=20; i++){
      |                    ~^~~~

• Subtask 1: 15 / 15
• Subtask 2: 75 / 85