Package g0301_0400.s0376_wiggle_subsequence

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    376 - Wiggle Subsequence\.

    Medium

    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.

    • For example, [1, 7, 4, 9, 2, 5] is a wiggle sequence because the differences (6, -3, 5, -7, 3) alternate between positive and negative.

    • In contrast, [1, 4, 7, 2, 5] and [1, 7, 4, 5, 5] are not wiggle sequences. The first is not because its first two differences are positive, and the second is not because its last difference is zero.

    A subsequence is obtained by deleting some elements (possibly zero) from the original sequence, leaving the remaining elements in their original order.

    Given an integer array nums, return the length of the longest wiggle subsequence of nums.

    Example 1:

    Input: nums = 1,7,4,9,2,5

    Output: 6

    Explanation: The entire sequence is a wiggle sequence with differences (6, -3, 5, -7, 3).

    Example 2:

    Input: nums = 1,17,5,10,13,15,10,5,16,8

    Output: 7

    Explanation: There are several subsequences that achieve this length. One is 1, 17, 10, 13, 10, 16, 8 with differences (16, -7, 3, -3, 6, -8).

    Example 3:

    Input: nums = 1,2,3,4,5,6,7,8,9

    Output: 2

    Constraints:

    • 1 <= nums.length <= 1000

    • 0 <= nums[i] <= 1000

    Follow up: Could you solve this in O(n) time?

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer wiggleMaxLength(IntArray nums)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait