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.
public class Solution {
public int ThirdMax(int[] nums) {
Array.Sort(nums);
Array.Reverse(nums);
int count = 1;
int num = nums[0];
for(int i=1;i<nums.Length;i++){
if(nums[i]!=num){
count++;
num=nums[i];
}
if(count==3){
break;
}
}
return count==3?num:nums[0];
}
}Time Complexity: O(nlogn)
Space Complexity: O(1)
