Introduction

In this blog post, we will explore how to solve the LeetCode problem "2750" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

You are given a binary array nums. A subarray of an array is good if it contains exactly one element with the value 1. Return an integer denoting the number of ways to split the array nums into good subarrays. As the number may be too large, return it modulo 109 + 7. A subarray is a contiguous non-empty sequence of elements within an array. Example 1: Input: nums = [0,1,0,0,1] Output: 3 Explanation: There are 3 ways to split nums into good subarrays: - [0,1] [0,0,1] - [0,1,0] [0,1] - [0,1,0,0] [1] Example 2: Input: nums = [0,1,0] Output: 1 Explanation: There is 1 way to split nums into good subarrays: - [0,1,0] Constraints: 1 <= nums.length <= 105 0 <= nums[i] <= 1

Explanation

Here's the solution to the problem:

• High-level approach:

  • Iterate through the array and identify the indices where the value is 1. These are the boundaries of our good subarrays.
  • Calculate the number of ways to split the array between consecutive 1s. The number of ways is the product of the number of zeros between each consecutive pair of 1s, plus 1.
  • Handle the case where there are no 1s in the array, in which case the number of ways to split the array is 0.

• Complexity:

  • Runtime Complexity: O(n)
  • Storage Complexity: O(1)

Code

    def numberOfWays(nums):
    ones = []
    for i, num in enumerate(nums):
        if num == 1:
            ones.append(i)

    if not ones:
        return 0

    n = len(ones)
    ans = 1
    mod = 10**9 + 7

    for i in range(n - 1):
        zeros = ones[i+1] - ones[i] - 1
        ans = (ans * (zeros + 1)) % mod

    return ans