Connectivity Problem

/*
This program reads a sequence of pairs of nonnegative integers less than N from standard input (interpreting the pair p q to mean "connect object p to object q") and prints out pairs
representing objects that are not yet connected. It maintains an array id that has an entry for each object, with the property that id[p] and id[q] are equal if and only if p and q are connected. For simplicity, we define N as a compile-time constant. Alternatively, we could take it from the input and allocate the id array
dynamically.From Algorithms in C++
*/

#include 
using namespace std;

static const int N = 10;
int main()
  { 
    int i, j, p, q, id[N];
    for (i = 0; i < N; i++) id[i] = i;
    
    while (cin >> p >> q)
    //Quick-find algorithm
   
    { 
        int t = id[p];
        if (t == id[q]) continue;
        for (i = 0; i < N; i++)
          if (id[i] == t) id[i] = id[q];
        cout << " " << p << " " << q << endl;
    }
  
    //Quick-union algorithm
/* { 
        for (i = p; i != id[i]; i = id[i]) ;
        for (j = q; j != id[j]; j = id[j]) ;
        if (i == j) continue;
        id[i] = j;
        cout << " " << p << " " << q << endl;
  }
*/

for ( i= 0; i < N; i ++ ) cout << i << " " ;
    cout << endl;


    for ( i= 0; i < N; i ++ ) cout << id[i] << " " ;
    cout << endl;
}