- Difficulty: Hard
- Tags: LeetCode, Hard, Stack, Array, Monotonic Stack, leetcode-1063, O(n), 🔒, Mono Stack
Problem
Given an integer array nums
, return the number of non-empty subarrays with the leftmost element of the subarray not larger than other elements in the subarray.
A subarray is a contiguous part of an array.
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Example 1:
Input: nums = [1,4,2,5,3] Output: 11 Explanation: There are 11 valid subarrays: [1],[4],[2],[5],[3],[1,4],[2,5],[1,4,2],[2,5,3],[1,4,2,5],[1,4,2,5,3].
Example 2:
Input: nums = [3,2,1] Output: 3 Explanation: The 3 valid subarrays are: [3],[2],[1].
Example 3:
Input: nums = [2,2,2] Output: 6 Explanation: There are 6 valid subarrays: [2],[2],[2],[2,2],[2,2],[2,2,2].
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Constraints:
1 <= nums.length <= 5 * 104
0 <= nums[i] <= 105