334. Increasing Triplet Subsequence

Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.

Formally the function should:

Return true if there exists  i, j, k 
such that  arr[i] <  arr[j] <  arr[k] given 0 ≤  i <  j <  k ≤  n-1 else return false.

Your algorithm should run in O(n) time complexity and O(1) space complexity.

Examples:
Given [1, 2, 3, 4, 5],
return true.

Given [5, 4, 3, 2, 1],
return false.

class Solution {
public:
    bool increasingTriplet(vector<int>& nums) {
        
        if(nums.size()<=2) return false;
        int c1=INT_MAX;
        int c2=INT_MAX;
        for(auto num:nums)
        {
            if(num<=c1)
                c1 = num;
            else if(num<=c2)
                c2 = num;
            else
                return true;
        }
        return false;
    }
};