Python实现删除排序数组中重复项的两种方法示例

本文实例讲述了Python实现删除排序数组中重复项的两种方法。分享给大家供大家参考，具体如下：

对于给定的有序数组nums，移除数组中存在的重复数字，确保每个数字只出现一次并返回新数组的长度

注意：不能为新数组申请额外的空间，只允许申请O（1）的额外空间修改输入数组

Example 1:

Given nums = [1,1,2],
Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.
It doesn't matter what you leave beyond

Example 2:

Given nums = [0,0,1,1,1,2,2,3,3,4],Your function should return length = 5, with the first five elements of nums being modified to 0, 1, 2, 3, and 4 respectively.
It doesn't matter what values are set beyond the returned length.

说明：为什么返回列表长度而不用返回列表？因为列表传入函数是以引用的方式传递的，函数中对列表进行的修改会被保留。

// nums is passed in by reference. (i.e., without making a copy)
int len = removeDuplicates(nums);
// any modification to nums in your function would be known by the caller.
// using the length returned by your function, it prints the first len elements.
for (int i = 0; i < len; i++) {
  print(nums[i]);
}

1. 简单判断列表中元素是否相等，相等就删除多余元素

def removeDuplicates(self, nums):
    """
    :type nums: List[int]
    :rtype: int
    """
    if not nums:
      return 0
    if len(nums)==1:  #单独判断列表长度为1的情况，因为之后的for循环从下标1开始
      return 1
    temp_num = nums[0]
    count =0     #for循环中动态删除列表元素，列表缩短，为了防止下标溢出需要用count标记删除元素个数
    for index, num in enumerate(nums[1:]):
      if temp_num == num:   #元素相等就删除
        del nums[index-count]
        count += 1
      else:
        temp_num = num
    return len(nums)
def removeDuplicates(self, nums):
    """
    :type nums: List[int]
    :rtype: int
    """
    forth = 0
    back = 1
    while back <= len(nums)-1:
      if nums[forth] == nums[back]:
        nums.pop(back)
      else:
        forth += 1
        back += 1
    return len(nums)

2. 修改数组，保证数组的前几个数字互不相同，且这几个数字的长度同返回长度相等

def removeDuplicates(self, nums):
    """
    :type nums: List[int]
    :rtype: int
    """
    if not nums:
      return 0
    length = 0   #不存在重复数字的数组长度
    for index in range(1,len(nums)):   #遍历数组
      if nums[index] != nums[length]:
        length += 1
        nums[length] = nums[index]
    return length+1

算法题来自：https://leetcode-cn.com/problems/remove-duplicates-from-sorted-array/description/