increasing_triplet_subsequence.cpp

class Solution {
public:
    bool increasingTriplet(vector<int>& nums) {
        if (nums.size() < 3) return false;
        int first = nums[0], second = INT_MAX;
        for (int i = 1; i < nums.size(); ++i) {
        	if (nums[i] > second) return true;
        	else if (nums[i] < first) first= nums[i];
        	else if (nums[i] > first && nums[i] < second) second = nums[i];
        }
        return false;
    }
};