Cod sursa(job #2114781)

Utilizator SederfoMarius Vlad Sederfo Data 25 ianuarie 2018 20:58:05
Problema Lowest Common Ancestor Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 0.89 kb
#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

ifstream fin ("lca.in");
ofstream fout ("lca.out");

int N, M;
int TT[100005], Level[100005];

vector <int> G[100005];



int LCA(int x, int y)
{
    while(Level[x]!=Level[y])
    {
        if (Level[x]>Level[y])
            x=TT[x];
        else
            y=TT[y];
    }
    while (x!=y)
    {
        x=TT[x];
        y=TT[y];
    }
    return x;
}

void DFS(int nod)
{
    for (int i=0; i<(int)G[nod].size(); i++)
    {
        Level[G[nod][i]]=Level[nod]+1;
        DFS(G[nod][i]);
    }
}

int main()
{
    fin >> N >> M;
    for (int i=2; i<=N; i++)
    {
        fin >> TT[i];
        G[TT[i]].push_back(i);
    }
    DFS(1);
    for (int i=1; i<=M; i++)
    {
        int x, y;
        fin >> x >> y;
        fout << LCA(x, y) << "\n";
    }
    return 0;
}