static int minOperation ( String str , int len ) {
  int first [ ] = new int [ MAX ] ;
  int last [ ] = new int [ MAX ] ;
  for ( int i = 0 ;
  i < MAX ;
  i ++ ) {
    first [ i ] = - 1 ;
    last [ i ] = - 1 ;
  }
  for ( int i = 0 ;
  i < len ;
  i ++ ) {
    int index = ( str . charAt ( i ) - 'a' ) ;
    if ( first [ index ] == - 1 ) first [ index ] = i ;
    last [ index ] = i ;
  }
  int minOp = - 1 ;
  for ( int i = 0 ;
  i < MAX ;
  i ++ ) {
    if ( first [ i ] == - 1 || first [ i ] == last [ i ] ) continue ;
    int cnt = len - ( last [ i ] - first [ i ] + 1 ) ;
    if ( minOp == - 1 || cnt < minOp ) minOp = cnt ;
  }
  return minOp ;
}

static int minOperation ( String str , int len ) { int first [ ] = new int [ MAX ] ; int last [ ] = new int [ MAX ] ; for ( int i = 0 ; i < MAX ; i ++ ) { first [ i ] = - 1 ; last [ i ] = - 1 ; } for ( int i = 0 ; i < len ; i ++ ) { int index = ( str . charAt ( i ) - ' a ' ) ; if ( first [ index ] == - 1 ) first [ index ] = i ; last [ index ] = i ; } int minOp = - 1 ; for ( int i = 0 ; i < MAX ; i ++ ) { if ( first [ i ] == - 1 || first [ i ] == last [ i ] ) continue ; int cnt = len - ( last [ i ] - first [ i ] + 1 ) ; if ( minOp == - 1 || cnt < minOp ) minOp = cnt ; } return minOp ; }
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