LeetCode:Increasing Triplet Subsequence

Increasing Triplet Subsequence

Total Accepted: 14818  Total Submissions: 43443  Difficulty: Medium

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.

Credits:
Special thanks to @DjangoUnchained for adding this problem and creating all test cases.

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Hide Similar Problems

  (M) Longest Increasing Subsequence

java code:

public class Solution {
    public boolean increasingTriplet(int[] nums) {
        
        int max = (1<<31)-1;
        int mid = (1<<31)-1;
        
        for(int num : nums) {
            if(num <= mid)
                mid = num;
            else if(num <= max)
                max = num;
            else
                return true;
        }
        
        return false;
    }
}