27. Remove Element

最新推荐文章于 2024-02-22 13:25:37 发布

原创最新推荐文章于 2024-02-22 13:25:37 发布 · 250 阅读

0 ·

CC 4.0 BY-SA版权

LeetCode-Python 专栏收录该内容

32 篇文章

订阅专栏

本文介绍了一种不使用额外内存空间的列表值删除算法，该算法可在原地修改输入列表以移除所有指定值的实例，并返回修改后列表的有效长度。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Given an array and a value, remove all instances of that value in place and return the new length.

Do not allocate extra space for another array, you must do this in place with constant memory.

The order of elements can be changed. It doesn't matter what you leave beyond the new length.

Example:
Given input array nums = [3,2,2,3], val = 3

Your function should return length = 2, with the first two elements of nums being 2.

翻译：从列表中删除给定的值，不得额外申请内存，返回前N个正确的值即可

思路：在原列表中进行操作，把要删除的元素和后面非目标元素进行互换即可

class Solution(object):
    def removeElement(self, nums, val):
        if not nums:
          return 0
        cnt = len(nums)
        flag_j = -1
        match = 0
        for i in range(cnt):
          if nums[i] == val:
            if i > flag_j:
              j = i+1
            else:
              j = flag_j+1
            while(j<cnt):
              if nums[j]!=nums[i]:
                nums[i] = nums[j]
                nums[j] = val
                flag_j = j
                break
              j+=1
        for i in range(cnt):
          if nums[i] != val:
            match+=1
          else:
            break
        return match