Number of Zero-Filled Subarrays — LeetCode 2348 Python Solution

The problem

Given an integer array nums, return the number of subarrays filled with 0. A subarray is a contiguous non-empty sequence of elements within an array.

Example

Input

nums = [1,3,0,0,2,0,0,4]

Output

6

Explanation

There are 4 occurrences of [0] as a subarray.

Python solution

class Solution:
    def zeroFilledSubarray(self, nums: List[int]) -> int:
        ans = cnt = 0
        for x in nums:
            if x == 0:
                cnt += 1
                ans += cnt
            else:
                cnt = 0
        return ans

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 2348. Number of Zero-Filled Subarrays is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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