Cod sursa(job #1556457)

Utilizator badea_adi1999Badea Adrian Catalin badea_adi1999 Data 24 decembrie 2015 21:52:46
Problema Lowest Common Ancestor Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 0.79 kb
//Lowest Common Ancestor
//Complexitate : Memorie O(n) , Timp O(n*m);
#include <cstdio>
#include <vector>
#define nmax 100005
using namespace std;
int n,m,t[nmax],g[nmax];
vector <int> v[nmax];
void dfs(int x)
{
    int i;
    for (i=0;i<v[x].size();i++) {
        g[v[x][i]]=g[x]+1;
        dfs(v[x][i]);
    }
}
int main()
{
    freopen("lca.in","r",stdin);
    freopen("lca.out","w",stdout);
    int i,j,a,b;
    scanf("%d %d",&n,&m);
    for (i=2;i<=n;i++) {
        scanf("%d",&t[i]);
        v[t[i]].push_back(i);
    }
    dfs(1);
    for (i=1;i<=m;i++) {
        scanf("%d %d",&a,&b);
        while (a!=b) {
            if (g[a]>g[b])
                a=t[a];
            else
                b=t[b];
            }
        printf("%d\n",a);
    }
    return 0;
}