41 - First Missing Positive
Written on October 21, 2015
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Given an unsorted integer array, find the first missing positive integer.
class Solution:
def firstMissingPositive(self, nums: List[int]) -> int:
for i in range(len(nums)):
while nums[i] > 0 and nums[i] <= len(nums) and nums[nums[i] - 1] != nums[i]:
nums[nums[i] - 1], nums[i] = nums[i], nums[nums[i] - 1]
for i, num in enumerate(nums):
if num != i + 1:
return i + 1
return len(nums) + 1