2020-03-13 Day 20: Leetcode 41.

class Solution:
    def firstMissingPositive(self, nums: List[int]) -> int:
        maxpos=0
        for num in nums:
            if num>maxpos:
                maxpos=num
        minpos=maxpos
        for num in nums:
            if num<minpos and num>0:
                minpos=num
        
        if minpos>1:
            return 1
        for i in range(minpos+1,maxpos+1):
            if i in nums:
                continue
            else:
                return i
        return maxpos+1