static int countPairsWithDiffK ( int arr [ ] , int n , int k ) {
  int count = 0 ;
  Arrays . sort ( arr ) ;
  int l = 0 ;
  int r = 0 ;
  while ( r < n ) {
    if ( arr [ r ] - arr [ l ] == k ) {
      count ++ ;
      l ++ ;
      r ++ ;
    }
    else if ( arr [ r ] - arr [ l ] > k ) l ++ ;
    else r ++ ;
  }
  return count ;
}

static int countPairsWithDiffK ( int arr [ ] , int n , int k ) { int count = 0 ; Arrays . sort ( arr ) ; int l = 0 ; int r = 0 ; while ( r < n ) { if ( arr [ r ] - arr [ l ] == k ) { count ++ ; l ++ ; r ++ ; } else if ( arr [ r ] - arr [ l ] > k ) l ++ ; else r ++ ; } return count ; }
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