Leetcode 41 缺失的第一个正整数

给你一个未排序的整数数组，请你找出其中没有出现的最小的正整数。

示例 1:

输入: [1,2,0]
输出: 3
示例 2:

输入: [3,4,-1,1]
输出: 2
示例 3:

输入: [7,8,9,11,12]
输出: 1

class Solution:

    def firstMissingPositive(self, nums: List[int]) -> int:

        if not nums or len(nums)==0:return 1

        i=0

        while i <len(nums):

            if nums[i]==i+1:

                i+=1

            elif nums[i]<=len(nums) and nums[i]>0:

                tmp=nums[nums[i]-1]

                if tmp==nums[i]:

                    i+=1

                    continue

                nums[nums[i]-1]=nums[i]

                nums[i]=tmp

            else:

                i+=1

        for i in range(len(nums)):

            if nums[i]!=i+1:

                return i+1

        return len(nums)+1