[Leetcode]414. Third Maximum Number

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.

此题思路与[Leetcode]26. Remove Duplicates from Sorted Array 类似。

class Solution {
    public int thirdMax(int[] nums) {
        Arrays.sort(nums);
        int index = 0;
        for (int i=1;i<nums.length;i++)
            if (nums[index]!=nums[i])
                nums[++index] = nums[i];
        return index<2? nums[index]:nums[index-2];
    }
}