Cod sursa(job #2099881)

Utilizator Alex18maiAlex Enache Alex18mai Data 4 ianuarie 2018 19:47:26
Problema Lowest Common Ancestor Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 0.82 kb
#include <fstream>
#include <vector>

using namespace std;

ifstream cin ("lca.in");
ofstream cout ("lca.out");

vector < vector < int > > gr(100100);
vector < int > dad (100100);
vector < int > lv (100100);

void dfs (int root){
    lv[root] = lv[dad[root]] + 1;
    for (auto &x : gr[root]){
        dfs(x);
    }
}

int main() {

    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    //BRUT

    int n , m;
    cin>>n>>m;

    for (int i=2; i<=n; i++){
        cin>>dad[i];
        gr[dad[i]].push_back(i);
    }

    dfs(1);

    for (int i=1; i<=m; i++){
        int x , y;
        cin>>x>>y;

        while (x != y){
            if (lv[x] > lv[y]){
                x = dad[x];
            }
            else{
                y = dad[y];
            }
        }

        cout<<x<<'\n';

    }

    return 0;
}