leetcode之Remove Linked List Elements-优快云博客

本文链接：https://blog.youkuaiyun.com/howtogetout/article/details/50027577

本文探讨了一种优化的链表元素移除算法实现方式，通过将链表转换为列表，删除指定元素后再转回链表，提高了算法效率。同时，提供了一个简化版的实现方法，减少了内存使用和提高了运行速度。

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这题我采用了另一个思路，转化为list，然后删除元素之后再按照list转回来。代码如下：

# 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
        """
        b = []
        if head == None:
            return None
        while head != None:
            b.append(head.val)
            head = head.next
        for i in range(len(b))[::-1]:
            if b[i] == val:
                del b[i]
        print b
        c = ListNode(0)
        a = c
        for i in b:
            a.next = ListNode(i)
            a = a.next
        return c.next

时间上耗费倒是挺多的，先尝试一下.

从另外一道题上得到了启发，于是修改了一下：

# 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
        """
        c = head
        if c == None:
            return None
        while c!= None:
            if c.next != None:
                if c.val == val:
                    c.val = c.next.val
                    c.next = c.next.next
                else:
                    c = c.next
            else:
                if c.val != val:
                    break
                else:
                    slow = head
                    fast = head
                    if slow.next == None:
                        return None
                    slow = slow.next
                    while slow.next != None:
                        slow = slow.next
                        fast = fast.next
                    fast.next = fast.next.next
                    break
                    
        return head