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
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