Cod sursa(job #2974124)

Utilizator alessiamtr12Mitrica Alessia alessiamtr12 Data 3 februarie 2023 11:01:25
Problema Lowest Common Ancestor Scor 90
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.82 kb
#include <fstream>
#include<vector>
#define NMAX 100001
using namespace std;
ifstream fin("lca.in");
ofstream fout("lca.out");
int n,m,q,x,y;
int nivel[NMAX],tata[NMAX];
vector<int>v[NMAX];
void dfs(int nod,int niv)
{
    nivel[nod]=niv;
    for(int i=0;i<v[nod].size();i++)
    {
        int nod1=v[nod][i];
        dfs(nod1,niv+1);
    }
}
int lca(int x,int y)
{
    if(nivel[x]<nivel[y])
        swap(x,y);

    while(nivel[x]>nivel[y])
        x=tata[x];
    while(x!=y)
    {
        x=tata[x];
        y=tata[y];
    }
    return x;
}
int main()
{
    fin>>n>>q;
    for(int i=2;i<=n;i++)
        {
            fin>>tata[i];
            v[tata[i]].push_back(i);
        }
    dfs(1,1);
    for(int i=1;i<=q;i++)
    {
        fin>>x>>y;
        fout<<lca(x,y)<<"\n";
    }
    return 0;
}