2348. Number of Zero-Filled Subarrays

Time: O(n)

Space: O(1)

Intuition

Count subarrays with exactly 0 odd numbers. A subarray is zero-odd if all elements are even. Count maximal even subarrays.

Algorithm

1For each maximal even subarray of length L: subarrays = L*(L+1)/2.

Common Pitfalls

•Split by odd numbers. Each even-only segment of length L contributes L*(L+1)/2 subarrays.

2348.cs

// Approach: Track consecutive zero runs; each run of length k contributes k*(k+1)/2 subarrays.
// Time: O(n) Space: O(1)

public class Solution
{
    public long ZeroFilledSubarray(int[] nums)
    {
        long totalCount = 0;  // Initialize total count of zero-filled subarrays
        int zeroCount = 0;    // Initialize count of consecutive zeros

        // Iterate through the array elements
        foreach (int value in nums)
        {
            // Reset zeroCount to 0 if the current element is not zero
            // Otherwise, increment zeroCount
            zeroCount = (value != 0) ? 0 : zeroCount + 1;
            // Add the current zeroCount to the total count
            totalCount += zeroCount;
        }

        return totalCount;  // Return the total count of zero-filled subarrays
    }
}

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