Cod sursa(job #3272941)

Utilizator Anul2024Anul2024 Anul2024 Data 31 ianuarie 2025 17:16:52
Problema Lowest Common Ancestor Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.26 kb
#include <fstream>
#include <vector>
#define dim 100000
using namespace std;
ifstream fin ("lca.in");
ofstream fout ("lca.out");
int n,q,x,y,viz[dim+1],sol[20*dim+1];
struct query
{
    int nod,pos;
};
vector <query> qry[dim+1];
vector <int> v[dim+1];
struct DSU
{
    int t[dim+1];
    void init ()
    {
        for (int i=1; i<=n; i++)
            t[i]=i;
    }
    int rad (int x)
    {
        if (x==t[x])
            return x;
        return t[x]=rad (t[x]);
    }
    void reun (int x,int y)
    {
        t[rad (y)]=rad (x);
    }
};
DSU pmd;
void dfs (int nod)
{
    viz[nod]=1;
    for (int i=0; i<(int)v[nod].size (); i++)
    {
        int vecin=v[nod][i];
        dfs (vecin);
        pmd.reun (nod,vecin);
    }
    for (int i=0; i<(int)qry[nod].size (); i++)
    {
        if (viz[qry[nod][i].nod])
            sol[qry[nod][i].pos]=pmd.rad (qry[nod][i].nod);
    }
}
int main()
{
    fin>>n>>q;
    pmd.init ();
    for (int i=2; i<=n; i++)
    {
        fin>>x;
        v[x].push_back (i);
    }
    for (int i=1; i<=q; i++)
    {
        fin>>x>>y;
        qry[x].push_back ({y,i});
        qry[y].push_back ({x,i});
    }
    dfs (1);
    for (int i=1; i<=q; i++)
        fout<<sol[i]<<"\n";
    return 0;
}