Problema A torneo N3 2014

#include <iostream>
#include <cstdio>
#define forn(i,n) for(int i=0; i<n; i++)
#define MAXN 17

using namespace std;

int ref[100000 + 100];
int tree[(1<<MAXN) + 100];

int n, q;

int solve(int);
int query(int, int);

int main()
{
    freopen("torneo.in", "r", stdin);
    freopen("torneo.out", "w", stdout);
    int x, y;

    cin >> n >> q;

    forn(i,(1<<n)){
        cin >> x;
        tree[(1<<(MAXN-1))+i] = x;
        ref[x] = i+1;
    }

    solve(1);

    cout << ref[ tree[1] ] << endl;

    forn(i,q){
        cin >> x >> y;
        cout << query(x,y) << endl;
    }

    return 0;
}

int query(int x, int y){
    int round = 1;
    int ind = (1<<(MAXN-1)) + x-1;
    ind /= 2; //para que no tome la base de la piramide and boom

    if( x == y ) return 0;

    while( ind ){
        if( (ref[tree[ind*2]]==y) || (ref[tree[ind*2+1]]==y) ) return round;

        round++;
        ind /= 2;
    }

    return 0;
}

int solve(int ind){
    int a, b;
    if( ind >= (1<<(MAXN-1)) ) return tree[ind];

    a = (tree[ind*2]) ? tree[ind*2] : solve(ind*2);
    b = (tree[ind*2+1]) ? tree[ind*2+1] : solve(ind*2+1);

    return tree[ind] = max(a,b);
}