LeetCode刷题(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.

很自然想到使用TreeSet进行数据存储。

public class Solution {    public int thirdMax(int[] nums) {        TreeSet ts = new TreeSet();        for(int x=0;x<nums.length;x++)        ts.add(nums[x]);        if(ts.size()<=2)        return (Integer)ts.last();        else         {            int y = (Integer)ts.pollLast();            int z = (Integer)ts.pollLast();            int v = (Integer)ts.pollLast();            return v;        }            }}

Submission Result: Accepted