Question

Source

• leetcode: Remove Linked List Elements | LeetCode OJ
• lintcode: (452) Remove Linked List Elements

Problem

Remove all elements from a linked list of integers that have value val .

Example

Given 1->2->3->3->4->5->3 , val = 3, you should return the list as 1->2->4->5

题解

删除链表中指定值，找到其前一个节点即可，将 next 指向下一个节点即可。

Python

# Definition for singly-linked list.
# class ListNode(object):
#   def __init__(self, x):
#     self.val = x
#     self.next = None

class Solution(object):
  def removeElements(self, head, val):
    """
    :type head: ListNode
    :type val: int
    :rtype: ListNode
    """
    dummy = ListNode(0)
    dummy.next = head
    curr = dummy
    while curr.next is not None:
      if curr.next.val == val:
        curr.next = curr.next.next
      else:
        curr = curr.next

    return dummy.next

Java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *   int val;
 *   ListNode next;
 *   ListNode(int x) { val = x; }
 * }
 */
public class Solution {
  /**
   * @param head a ListNode
   * @param val an integer
   * @return a ListNode
   */
  public ListNode removeElements(ListNode head, int val) {
    ListNode dummy = new ListNode(0);
    dummy.next = head;
    ListNode curr = dummy;
    while (curr.next != null) {
      if (curr.next.val == val) {
        curr.next = curr.next.next;
      } else {
        curr = curr.next;
      }
    }

    return dummy.next;
  }
}

源码分析

while 循环中使用 curr.next 较为方便，if 语句中比较时也使用 curr.next.val 也比较简洁，如果使用 curr 会比较难处理。

复杂度分析

略