414. Third Maximum Number

#### QUESTION:

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.
``````

#### SOLUTION:

``````public class Solution {
public int thirdMax(int[] nums) {
long first = Long.MIN_VALUE;
long second = Long.MIN_VALUE;
long third = Long.MIN_VALUE;
for(int i = 0;i<nums.length;i++){
int num = nums[i];
if(num>third){
if(num>second){
if(num>first){
third = second;
second = first;
first = num;
}else if(num!=first){
third = second;
second = num;
}
}else if(num!=second){
third = num;
}
}
}
return third == Long.MIN_VALUE ? (int) first : (int)third;
}
}
``````
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