Python3 代码

```
class Solution(object):
def getMissingNumber(self, nums):
“”“
:type nums: List[int]
:rtype: int
“”“
if len(nums) == 0:
return 0

    x = -1
    for i in range (0, len(nums)):
        if nums [i] != i:
            x = i
            break

    if x == -1:
        return len(nums)
    else:
        return x```