2444. Count Subarrays With Fixed Bounds

Problem Link

Description

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You are given an integer array nums and two integers minK and maxK.

A fixed-bound subarray of nums is a subarray that satisfies the following conditions:

• The minimum value in the subarray is equal to minK.
• The maximum value in the subarray is equal to maxK.

Return the number of fixed-bound subarrays.

A subarray is a contiguous part of an array.

 

Example 1:

Input: nums = [1,3,5,2,7,5], minK = 1, maxK = 5
Output: 2
Explanation: The fixed-bound subarrays are [1,3,5] and [1,3,5,2].

Example 2:

Input: nums = [1,1,1,1], minK = 1, maxK = 1
Output: 10
Explanation: Every subarray of nums is a fixed-bound subarray. There are 10 possible subarrays.

 

Constraints:

• 2 <= nums.length <= 105
• 1 <= nums[i], minK, maxK <= 106

Solution

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Python3

class Solution:
    def countSubarrays(self, nums: List[int], minK: int, maxK: int) -> int:
        N = len(nums)
        minPos = maxPos = -1
        i = res = 0
 
        for j, x in enumerate(nums):
            if x == minK:
                minPos = j
            
            if x == maxK:
                maxPos = j
            
            if x < minK or x > maxK:
                i = j + 1
            
            res += max(0, min(minPos, maxPos) - i + 1)
 
        return res