标签：des style class blog code ext
Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the original relative order of the nodes in each of the two partitions. For example, Given 1->4->3->2->5->2 and x = 3, return 1->2->2->4->3->5.
Analysis: Linked List 惯用套路，Runner Technique(Two Pointers), 一些技巧就是：设置head的前置假节点prev，两个pointer：current和runner都指到这个prev，然后进行判断总是判断 current.next 或者 runner.next. 这样做按照我多次做类似题的经验来说，是最方便省事不容易出错的。这道题一次过。思路就是current 和 runner 一直移动直到找到 current.next >= x 为止，这里就是后面小于x的元素将要插入的位置，current便停在这里，指示这个位置，runner继续往后面寻找，把每一个小于x的元素都插入到current.next 的位置。
1 /** 2 * Definition for singly-linked list. 3 * public class ListNode { 4 * int val; 5 * ListNode next; 6 * ListNode(int x) { 7 * val = x; 8 * next = null; 9 * } 10 * } 11 */ 12 public class Solution { 13 public ListNode partition(ListNode head, int x) { 14 ListNode prev = new ListNode(-1); 15 prev.next = head; 16 ListNode current = prev; 17 ListNode runner = prev; 18 while (current.next != null && current.next.val < x) { 19 current = current.next; 20 runner = runner.next; 21 } 22 while (runner.next != null) { 23 if (runner.next.val < x) { 24 ListNode temp = runner.next; 25 runner.next = runner.next.next; 26 temp.next = current.next; 27 current.next = temp; 28 current = current.next; 29 } 30 else runner = runner.next; 31 } 32 return prev.next; 33 } 34 }
Leetcode: Partition List,布布扣,bubuko.com
标签：des style class blog code ext
原文地址：http://www.cnblogs.com/EdwardLiu/p/3807137.html
