lc414. Third Maximum Number

414. Third Maximum Number Easy

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Share Given a non-empty array of integers, return the third maximum number in this array. If it does not exist, return the maximum number. The time complexity must be in O(n).

Example 1: Input: [3, 2, 1]

Output: 1

Explanation: The third maximum is 1. Example 2: Input: [1, 2]

Output: 2

Explanation: The third maximum does not exist, so the maximum (2) is returned instead. Example 3: Input: [2, 2, 3, 1]

Output: 1

Explanation: Note that the third maximum here means the third maximum distinct number. Both numbers with value 2 are both considered as second maximum.

思路：集合过滤重复数字，而后转换为数组，排序，大于等于三个，输出第三个，不然输出第一个元素 代码：python3

class Solution:
    def thirdMax(self, nums):
        s = set(nums)
        arr=list(s)
        arr.sort(reverse=True)
        if len(arr)>=3:
        	return arr[2]
        else:
        	return arr[0]
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