[leetcode]414. Third Maximum Number

题目链接:https://leetcode.com/problems/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: 1Explanation: The third maximum is 1.

Example 2:

Input: [1, 2]Output: 2Explanation: The third maximum does not exist, so the maximum (2) is returned instead.

Example 3:

Input: [2, 2, 3, 1]Output: 1Explanation: Note that the third maximum here means the third maximum distinct number.Both numbers with value 2 are both considered as second maximum.

class Solution{public:    int thirdMax(vector<int>& nums)    {        int result=0;        int len=nums.size();        int first=INT_MIN,second=INT_MIN,third=INT_MIN;        int count=0,bottom=0;        if(len==1)            return nums[0];        else if(len==2)            return max(nums[0],nums[1]);        else        {            for(int i=0;i<len;i++)            {                                if(nums[i]==INT_MIN)                    bottom=1;                if(nums[i]==first||nums[i]==second||nums[i]==third)                    continue;                if(nums[i]>first)                {                    third=second;                    second=first;                    first=nums[i];                    count++;                }                else if(nums[i]>second)                {                    third=second;                    second=nums[i];                    count++;                }                else if(nums[i]>third)                {                    third=nums[i];                    count++;                }            }            if(count+bottom>=3)                result=third;            else                result=first;            return result;        }    }};