Section 1Understand Problem
Section 01
Understand the problem
Restate the problem precisely. Interviewers reward candidates who pause, define the contract, and name the guarantees before coding.
Problem statement
A *wiggle sequence* is a sequence where the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either positive or negative. A sequence with one element and a sequence with two non-equal elements are trivially wiggle sequences. Given an integer array `nums`, return the length of the longest wiggle subsequence of `nums`.
Example
nums = [1,7,4,9,2,5] → 6
Constraints
1 ≤ nums.length ≤ 1000 · 0 ≤ nums[i] ≤ 1000
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