Given an unsorted integer array, find the smallest missing positive integer.
Example 1:
Input: [1,2,0] Output: 3
Example 2:
Input: [3,4,-1,1] Output: 2
Example 3:
Input: [7,8,9,11,12] Output: 1
Note:
Your algorithm should run in O(n) time and uses constant extra space.
解答:
class Solution: def firstMissingPositive(self, nums): """ :type nums: List[int] :rtype: int """ i = 0 length = len(nums) while i < length: if nums[i] == i + 1 or nums[i] > length or nums[i] <= 0: i += 1 else: index = nums[i] - 1 if nums[index] == nums[i]: i += 1 continue nums[i], nums[index] = nums[index], nums[i] min = 1 i = 0 while i < length and nums[i] == i + 1 : i += 1 return i + 1