Introduction

In this blog post, we will explore how to solve the LeetCode problem "1689" 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

A decimal number is called deci-binary if each of its digits is either 0 or 1 without any leading zeros. For example, 101 and 1100 are deci-binary, while 112 and 3001 are not. Given a string n that represents a positive decimal integer, return the minimum number of positive deci-binary numbers needed so that they sum up to n. Example 1: Input: n = "32" Output: 3 Explanation: 10 + 11 + 11 = 32 Example 2: Input: n = "82734" Output: 8 Example 3: Input: n = "27346209830709182346" Output: 9 Constraints: 1 <= n.length <= 105 n consists of only digits. n does not contain any leading zeros and represents a positive integer.

Explanation

Here's the breakdown of the solution:

• Key Idea: The minimum number of deci-binary numbers needed is simply the largest digit in the input string. This is because we can always decompose the number such that each deci-binary number contributes 1 to each digit place up to the maximum digit.
• Example: For "32", we need three deci-binary numbers. We can represent 32 as 10 + 11 + 11. The maximum digit is 3.

• Implementation: Iterate through the string and find the maximum digit.

• Complexity: O(N) time complexity, where N is the length of the string. O(1) space complexity.

Code

    def minPartitions(n: str) -> int:
    """
    Given a string n that represents a positive decimal integer,
    return the minimum number of positive deci-binary numbers needed so that they sum up to n.
    """
    max_digit = 0
    for digit in n:
        max_digit = max(max_digit, int(digit))
    return max_digit