AashishPalSingh / DS-and-Algos

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Longest Zig-Zag Sub Sequence #21

Open AashishPalSingh opened 4 years ago

AashishPalSingh commented 4 years ago

https://practice.geeksforgeeks.org/problems/longest-zig-zag-sub-sequence/0

Given an array A of N positive integers. The task is to find the longest Zig-Zag subsequence problem such that all elements of this are alternating (Ai-1 < Ai > Ai+1).

Input: The first line of input contains an integer T denoting the number of test cases. Each test case contains an integer N which denotes the number of elements in the array A. Next line contains space separated n elements in the array A.​

Output: Print the length of the longest such subsequence.

Constraints: 1 <= T <= 200 1 <= N <= 103 1 <= Ai <= 105

Example: Input: 2 6 5 5 10 100 10 5 3 1 2 3

Output: 3 2

Explanation: Testcase 1: 5, 10, 5 is the longest common subsequence with elements alternating.