Convert Date to Binary

Difficulty: Easy | Acceptance: 88.80% | Paid: No Topics: Math, String

You are given a string date in the format YYYY-MM-DD (for example, 2024-02-16).

Convert the date string to the format of binary representation and return the result.

The binary representation of a number is the representation of that number in base-2. For example, the binary representation of 5 is “101”, and the binary representation of 10 is “1010”.

• Examples
• Constraints
• Approach 1: Built-in Conversion
• Approach 2: Manual Binary Conversion

Examples

Example 1:

Input: date = "2080-02-10"
Output: "100000100000-10-1010"
Explanation:
2080 in binary is "100000100000".
02 in binary is "10".
10 in binary is "1010".

Example 2:

Input: date = "1900-01-01"
Output: "11101101100-1-1"
Explanation:
1900 in binary is "11101101100".
01 in binary is "1".
01 in binary is "1".

Constraints

- date.length == 10
- date[4] == date[7] == '-', and all other date[i]'s are digits.
- The input is generated such that date represents a valid Gregorian calendar date between Jan 1^st, 1900 and Dec 31^st, 2100 (both inclusive).

Approach 1: Built-in Conversion

Intuition Most modern programming languages provide built-in utilities to convert integers to binary strings. We can leverage these standard library functions to parse the date components and convert them directly.

Steps

• Split the input string by the delimiter ’-’ to separate year, month, and day.
• Parse the resulting substrings into integers.
• Use the language’s built-in method (e.g., bin(), Integer.toBinaryString(), toString(2)) to convert each integer to its binary string representation.
• Join the three binary strings with ’-’ and return the result.

class Solution:
    def convertDateToBinary(self, date: str) -> str:
        y, m, d = date.split('-')
        return bin(int(y))[2:] + '-' + bin(int(m))[2:] + '-' + bin(int(d))[2:]

Complexity

• Time: O(1) - The number of operations is constant and bounded by the maximum value of the year (2100), which has a fixed number of bits.
• Space: O(1) - The space used for the output string is constant in size relative to the input constraints.
• Notes: This approach is the most concise and readable for production code.

Approach 2: Manual Binary Conversion

Intuition We can implement the mathematical process of converting a decimal number to binary manually. This involves repeatedly dividing the number by 2 and recording the remainders.

Steps

• Parse the year, month, and day from the string.
• For each number, initialize an empty string to store the binary result.
• While the number is greater than 0:
  • Prepend the remainder of the number divided by 2 (n % 2) to the result string.
  • Update the number by integer division by 2 (n /= 2).
• Join the resulting binary strings with ’-‘.

class Solution:
    def convertDateToBinary(self, date: str) -> str:
        def to_bin(n):
            if n == 0: return '0'
            res = ''
            while n > 0:
                res = str(n % 2) + res
                n //= 2
            return res

        y, m, d = date.split('-')
        return to_bin(int(y)) + '-' + to_bin(int(m)) + '-' + to_bin(int(d))

Complexity

• Time: O(1) - The loop runs for log₂(n) iterations, where n is at most 2100. This is a constant upper bound.
• Space: O(1) - Excluding the output string, we use only a few variables for computation.
• Notes: This approach demonstrates the underlying algorithm and is useful if built-in functions are restricted.