static boolean checkIsAP ( int arr [ ] , int n ) {
  if ( n == 1 ) return true ;
  Arrays . sort ( arr ) ;
  int d = arr [ 1 ] - arr [ 0 ] ;
  for ( int i = 2 ;
  i < n ;
  i ++ ) if ( arr [ i ] - arr [ i - 1 ] != d ) return false ;
  return true ;
}

static boolean checkIsAP ( int arr [ ] , int n ) { if ( n == 1 ) return true ; Arrays . sort ( arr ) ; int d = arr [ 1 ] - arr [ 0 ] ; for ( int i = 2 ; i < n ; i ++ ) if ( arr [ i ] - arr [ i - 1 ] != d ) return false ; return true ; }
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