Case | Javascript implementation of the approach ; Function to return the sorted string ; To store the frequencies of the lowercase and the uppercase characters in the given string ; If current character is lowercase then increment its frequency in the lower [ ] array ; Else increment in the upper [ ] array ; Pointers that point to the smallest lowercase and the smallest uppercase characters respectively in the given string ; For every character in the given string ; If the current character is lowercase then replace it with the smallest lowercase character available ; Decrement the frequency of the used character ; Else replace it with the smallest uppercase character available ; Decrement the frequency of the used character ; Return the sorted string ; Driver code
var MAX = 26 ; function getSortedString ( s , n ) { var lower = Array ( MAX ) . fill ( 0 ) ; var upper = Array ( MAX ) . fill ( 0 ) ; for ( var i = 0 ; i < n ; i ++ ) { if ( ( s [ i ] ) == s [ i ] . toLowerCase ( ) ) lower [ s [ i ] . charCodeAt ( 0 ) - ' ' . charCodeAt ( 0 ) ] ++ ; else if ( s [ i ] = s [ i ] . toUpperCase ( ) ) upper [ s [ i ] . charCodeAt ( 0 ) - ' ' . charCodeAt ( 0 ) ] ++ ; } var i = 0 , j = 0 ; while ( i < MAX && lower [ i ] == 0 ) i ++ ; while ( j < MAX && upper [ j ] == 0 ) j ++ ; for ( var k = 0 ; k < n ; k ++ ) { if ( s [ k ] == s [ k ] . toLowerCase ( ) ) { while ( lower [ i ] == 0 ) i ++ ; s [ k ] = String . fromCharCode ( i + ' ' . charCodeAt ( 0 ) ) ; lower [ i ] -- ; } else if ( s [ k ] == s [ k ] . toUpperCase ( ) ) { while ( upper [ j ] == 0 ) j ++ ; s [ k ] = String . fromCharCode ( j + ' ' . charCodeAt ( 0 ) ) ; upper [ j ] -- ; } } return s . join ( ' ' ) ; } var s = " " ; var n = s . length ; document . write ( getSortedString ( s . split ( ' ' ) , n ) ) ;