https://leetcode.com/problems/partition-list/description/
Given a linked list and a target value T, partition it such that all nodes less than T are listed before the nodes larger than or equal to target value T. The original relative order of the nodes in each of the two partitions should be preserved.
Examples
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L = 2 -> 4 -> 3 -> 5 -> 1 -> null, T = 3, is partitioned to 2 -> 1 -> 4 -> 3 -> 5 -> null
1 public ListNode partition(ListNode head, int target) { 2 // Write your solution here 3 if(head == null || head.next == null) return head ; 4 ListNode smallHead = new ListNode(0), 5 smallCurr = smallHead, 6 largeHead = new ListNode(0), 7 largeCurr = largeHead, 8 curr = head ; 9 //no need to keep head 10 while(curr != null){ 11 if(curr.value<target){ 12 smallCurr.next = curr ; 13 smallCurr = smallCurr.next ; 14 } else{ 15 largeCurr.next = curr ; 16 largeCurr = largeCurr.next ; 17 } 18 curr = curr.next; 19 } 20 //this is super important! otherwise circle! 21 largeCurr.next = null ; 22 //用dummy 的好处，不用担心 small 里到底有没有值 23 smallCurr.next = largeHead.next ; 24 return smallHead.next ; 25 }