2762. Continuous Subarrays

Problem Link

Description

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You are given a 0-indexed integer array nums. A subarray of nums is called continuous if:

• Let i, i + 1, ..., j be the indices in the subarray. Then, for each pair of indices i <= i1, i2 <= j, 0 <= |nums[i1] - nums[i2]| <= 2.

Return the total number of continuous subarrays.

A subarray is a contiguous non-empty sequence of elements within an array.

 

Example 1:

Input: nums = [5,4,2,4]
Output: 8
Explanation: 
Continuous subarray of size 1: [5], [4], [2], [4].
Continuous subarray of size 2: [5,4], [4,2], [2,4].
Continuous subarray of size 3: [4,2,4].
There are no subarrys of size 4.
Total continuous subarrays = 4 + 3 + 1 = 8.
It can be shown that there are no more continuous subarrays.

 

Example 2:

Input: nums = [1,2,3]
Output: 6
Explanation: 
Continuous subarray of size 1: [1], [2], [3].
Continuous subarray of size 2: [1,2], [2,3].
Continuous subarray of size 3: [1,2,3].
Total continuous subarrays = 3 + 2 + 1 = 6.

 

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 109

Solution

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Python3

from sortedcontainers import SortedList
 
class Solution:
    def continuousSubarrays(self, nums: List[int]) -> int:
        N = len(nums)
        res = 0
        i = 0
        sl = SortedList()
        
        
        for j, x in enumerate(nums):
            sl.add(x)
            
            while len(sl) >= 2 and sl[-1] - sl[0] > 2:
                sl.remove(nums[i])
                i += 1
            
            res += j - i + 1
        
        return res