Leetcode 还未解决的bug

27. Remove Element

val = 1
nums = [1,1,2,3]
for i in nums:
    if i == val:
        nums.remove(i)

a = nums

result :

val = 1
nums = [1,1,2,3]
for i in nums[:]:
    if i == val:
        nums.remove(i)

a = nums

result:

不用remove的解法：

class Solution(object):
    def removeElement(self, nums, val):
        """
        :type nums: List[int]
        :rtype: int
        """
        if not nums:
            return 0
        tail = 0
        for i in range(len(nums)):
            if nums[i]!=val:
                nums[tail]=nums[i]
                tail+=1
        return tail  

当 return错误数 的时候，有可能会产生index out of range