{ "data": { "question": { "questionId": "2022", "questionFrontendId": "1911", "boundTopicId": null, "title": "Maximum Alternating Subsequence Sum", "titleSlug": "maximum-alternating-subsequence-sum", "content": "

The alternating sum of a 0-indexed array is defined as the sum of the elements at even indices minus the sum of the elements at odd indices.

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Given an array nums, return the maximum alternating sum of any subsequence of nums (after reindexing the elements of the subsequence).

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A subsequence of an array is a new array generated from the original array by deleting some elements (possibly none) without changing the remaining elements' relative order. For example, [2,7,4] is a subsequence of [4,2,3,7,2,1,4] (the underlined elements), while [2,4,2] is not.

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Example 1:

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\r\nInput: nums = [4,2,5,3]\r\nOutput: 7\r\nExplanation: It is optimal to choose the subsequence [4,2,5] with alternating sum (4 + 5) - 2 = 7.\r\n
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Example 2:

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\r\nInput: nums = [5,6,7,8]\r\nOutput: 8\r\nExplanation: It is optimal to choose the subsequence [8] with alternating sum 8.\r\n
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Example 3:

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\r\nInput: nums = [6,2,1,2,4,5]\r\nOutput: 10\r\nExplanation: It is optimal to choose the subsequence [6,1,5] with alternating sum (6 + 5) - 1 = 10.\r\n
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Constraints:

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