LeetCode[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) {        int small = INT_MAX, big = INT_MAX;          for(auto i: nums)          {              if(i <= small)                 small = val;              else if(i <= big)                 big = val;              else                 return true;          }          return false;      }};