Arrange consonants and vowels nodes in a linked list | Java program to arrange consonants and vowels nodes in a linked list ; A linked list node ; Function to add new node to the List ; utility function to print linked list ; utility function for checking vowel ; function to arrange consonants and vowels nodes ; for keep track of vowel ; list is empty ; We need to discover the first vowel in the list . It is going to be the returned head , and also the initial latestVowel . ; first element is a vowel . It will also be the new head and the initial latestVowel ; ; First element is not a vowel . Iterate through the list until we find a vowel . Note that curr points to the element * before * the element with the vowel . ; This is an edge case where there are only consonants in the list . ; Set the initial latestVowel and the new head to the vowel item that we found . Relink the chain of consonants after that vowel item : old_head_consonant -> consonant1 -> consonant2 -> vowel -> rest_of_list becomes vowel -> old_head_consonant -> consonant1 -> consonant2 -> rest_of_list ; Now traverse the list . Curr is always the item * before * the one we are checking , so that we can use it to re - link . ; The next discovered item is a vowel ; If it comes directly after the previous vowel , we don 't need to  move items around, just mark the  new latestVowel and advance curr. ; But if it comes after an intervening chain of consonants , we need to chain the newly discovered vowel right after the old vowel . Curr is not changed as after the re - linking it will have a new next , that has not been checked yet , and we always keep curr at one before the next to check . ; Chain in new vowel ; Advance latestVowel ; Remove found vowel from previous place ; Re - link chain of consonants after latestVowel ; No vowel in the next element , advance curr . ; Driver code
class GfG { static class Node { char data ; Node next ; } static Node newNode ( char key ) { Node temp = new Node ( ) ; temp . data = key ; temp . next = null ; return temp ; } static void printlist ( Node head ) { if ( head == null ) { System . out . println ( " Empty ▁ List " ) ; return ; } while ( head != null ) { System . out . print ( head . data + " ▁ " ) ; if ( head . next != null ) System . out . print ( " - > ▁ " ) ; head = head . next ; } System . out . println ( ) ; } static boolean isVowel ( char x ) { return ( x == ' a ' x == ' e ' x == ' i ' x == ' o ' x == ' u ' ) ; } static Node arrange ( Node head ) { Node newHead = head ; Node latestVowel ; Node curr = head ; if ( head == null ) return null ; if ( isVowel ( head . data ) == true ) latestVowel = head ; else { while ( curr . next != null && ! isVowel ( curr . next . data ) ) curr = curr . next ; if ( curr . next == null ) return head ; latestVowel = newHead = curr . next ; curr . next = curr . next . next ; latestVowel . next = head ; } while ( curr != null && curr . next != null ) { if ( isVowel ( curr . next . data ) == true ) { if ( curr == latestVowel ) { latestVowel = curr = curr . next ; } else { Node temp = latestVowel . next ; latestVowel . next = curr . next ; latestVowel = latestVowel . next ; curr . next = curr . next . next ; latestVowel . next = temp ; } } else { curr = curr . next ; } } return newHead ; } public static void main ( String [ ] args ) { Node head = newNode ( ' a ' ) ; head . next = newNode ( ' b ' ) ; head . next . next = newNode ( ' c ' ) ; head . next . next . next = newNode ( ' e ' ) ; head . next . next . next . next = newNode ( ' d ' ) ; head . next . next . next . next . next = newNode ( ' o ' ) ; head . next . next . next . next . next . next = newNode ( ' x ' ) ; head . next . next . next . next . next . next . next = newNode ( ' i ' ) ; System . out . println ( " Linked ▁ list ▁ before ▁ : ▁ " ) ; printlist ( head ) ; head = arrange ( head ) ; System . out . println ( " Linked ▁ list ▁ after ▁ : " ) ; printlist ( head ) ; } }