Leetcode•Sep 06, 2025
Increasing Triplet Subsequence
Hazrat Ali
Leetcode
Given an integer array nums, return true if there exists a triple of indices (i, j, k) such that i < j < k and nums[i] < nums[j] < nums[k]. If no such indices exists, return false.
Example 1:
Input: nums = [1,2,3,4,5] Output: true Explanation: Any triplet where i < j < k is valid.
Example 2:
Input: nums = [5,4,3,2,1] Output: false Explanation: No triplet exists.
Example 3:
Input: nums = [2,1,5,0,4,6] Output: true Explanation: One of the valid triplet is (3, 4, 5), because nums[3] == 0 < nums[4] == 4 < nums[5] == 6.
Solution
/**
* @param {number[]} nums
* @return {boolean}
*/
const increasingTriplet = nums => {
let n1 = Infinity;
let n2 = Infinity;
for (let num of nums) {
if (num <= n1) {
n1 = num;
} else if (num <= n2) {
n2 = num;
} else {
return true;
}
}
return false;
};