Cod sursa(job #2157428)

Utilizator mateigabriel99Matei Gabriel mateigabriel99 Data 9 martie 2018 16:56:12
Problema Lowest Common Ancestor Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 0.89 kb
#include <bits/stdc++.h>

using namespace std;

const int NMax=100005;
const int H=200;

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

int N,M;
vector<int> G[NMax];
int T[NMax],T2[NMax],level[NMax];

void DFS(int node,int father,int lvl)
{
    level[node]=lvl;
    T2[node]=father;
    for(auto child : G[node])
        DFS(child,node,lvl+1);
}

int LCA(int x,int y)
{
    while(T2[x]!=T2[y])
        if(level[x]>level[y])
            x=T2[x];
        else
            y=T2[y];
    while(x!=y)
        if(level[x]>level[y])
            x=T[x];
        else
            y=T[y];
    return x;

}

int main()
{
    fin>>N>>M;
    for(int i=2;i<=N;i++)
    {
        fin>>T[i];
        G[T[i]].push_back(i);
    }

    DFS(1,0,0);

    for(int i=1;i<=M;i++)
    {
        int x,y;
        fin>>x>>y;
        fout<<LCA(x,y)<<"\n";
    }

    return 0;
}