{ "data": { "question": { "questionId": "3252", "questionFrontendId": "2970", "categoryTitle": "Algorithms", "boundTopicId": 2575513, "title": "Count the Number of Incremovable Subarrays I", "titleSlug": "count-the-number-of-incremovable-subarrays-i", "content": "
You are given a 0-indexed array of positive integers nums
.
A subarray of nums
is called incremovable if nums
becomes strictly increasing on removing the subarray. For example, the subarray [3, 4]
is an incremovable subarray of [5, 3, 4, 6, 7]
because removing this subarray changes the array [5, 3, 4, 6, 7]
to [5, 6, 7]
which is strictly increasing.
Return the total number of incremovable subarrays of nums
.
Note that an empty array is considered strictly increasing.
\n\nA subarray is a contiguous non-empty sequence of elements within an array.
\n\n\n
Example 1:
\n\n\nInput: nums = [1,2,3,4]\nOutput: 10\nExplanation: The 10 incremovable subarrays are: [1], [2], [3], [4], [1,2], [2,3], [3,4], [1,2,3], [2,3,4], and [1,2,3,4], because on removing any one of these subarrays nums becomes strictly increasing. Note that you cannot select an empty subarray.\n\n\n
Example 2:
\n\n\nInput: nums = [6,5,7,8]\nOutput: 7\nExplanation: The 7 incremovable subarrays are: [5], [6], [5,7], [6,5], [5,7,8], [6,5,7] and [6,5,7,8].\nIt can be shown that there are only 7 incremovable subarrays in nums.\n\n\n
Example 3:
\n\n\nInput: nums = [8,7,6,6]\nOutput: 3\nExplanation: The 3 incremovable subarrays are: [8,7,6], [7,6,6], and [8,7,6,6]. Note that [8,7] is not an incremovable subarray because after removing [8,7] nums becomes [6,6], which is sorted in ascending order but not strictly increasing.\n\n\n
\n
Constraints:
\n\n1 <= nums.length <= 50
1 <= nums[i] <= 50
给你一个下标从 0 开始的 正 整数数组 nums
。
如果 nums
的一个子数组满足:移除这个子数组后剩余元素 严格递增 ,那么我们称这个子数组为 移除递增 子数组。比方说,[5, 3, 4, 6, 7]
中的 [3, 4]
是一个移除递增子数组,因为移除该子数组后,[5, 3, 4, 6, 7]
变为 [5, 6, 7]
,是严格递增的。
请你返回 nums
中 移除递增 子数组的总数目。
注意 ,剩余元素为空的数组也视为是递增的。
\n\n子数组 指的是一个数组中一段连续的元素序列。
\n\n\n\n
示例 1:
\n\n\n输入:nums = [1,2,3,4]\n输出:10\n解释:10 个移除递增子数组分别为:[1], [2], [3], [4], [1,2], [2,3], [3,4], [1,2,3], [2,3,4] 和 [1,2,3,4]。移除任意一个子数组后,剩余元素都是递增的。注意,空数组不是移除递增子数组。\n\n\n
示例 2:
\n\n\n输入:nums = [6,5,7,8]\n输出:7\n解释:7 个移除递增子数组分别为:[5], [6], [5,7], [6,5], [5,7,8], [6,5,7] 和 [6,5,7,8] 。\nnums 中只有这 7 个移除递增子数组。\n\n\n
示例 3:
\n\n\n输入:nums = [8,7,6,6]\n输出:3\n解释:3 个移除递增子数组分别为:[8,7,6], [7,6,6] 和 [8,7,6,6] 。注意 [8,7] 不是移除递增子数组因为移除 [8,7] 后 nums 变为 [6,6] ,它不是严格递增的。\n\n\n
\n\n
提示:
\n\n1 <= nums.length <= 50
1 <= nums[i] <= 50
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