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Delete One '5' From a Digit String to Get the Largest Number

CohereSoftware Engineer · Onsite
MediumSoftware EngineerOnsiteCoding & Algorithms

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Given a digit string containing at least one 5, delete exactly one 5 so the remaining string has the largest possible numeric value, keeping any leading zeros. This intern online-assessment problem tests reasoning about how each digit position affects a number and careful handling of repeated digits.

You are given a string digits made up of decimal digits that contains at least one '5'. Delete exactly one occurrence of the character '5' from digits and return the resulting string whose numeric value is as large as possible.

Function Signature

def max_after_deleting_five(digits: str) -> str:

Rules

  • Exactly one '5' is deleted. No other character is removed, added or reordered.
  • Every possible result has length len(digits) - 1, so comparing two results numerically is the same as comparing them character by character from the left.
  • The returned string keeps any leading zeros the deletion produces. For example, deleting the only '5' from "503" returns "03".
  • Different deletions can produce the same string (either '5' in "55" gives "5"). The answer is that string, so the output is always unique.

Constraints

  • 2 <= len(digits) <= 100000
  • Every character of digits is one of '0' through '9'.
  • digits[0] != '0'
  • digits contains at least one '5'.

Examples

Example 1

  • Input: digits = "15958"
  • Output: "1958"
  • Explanation: Deleting the '5' at index 1 gives "1958", and deleting the '5' at index 3 gives "1598". The larger value is "1958".

Example 2

  • Input: digits = "5505"
  • Output: "550"
  • Explanation: Deleting the '5' at index 0 or index 1 gives "505", and deleting the '5' at index 3 gives "550", which is larger.

Example 3

  • Input: digits = "503"
  • Output: "03"
  • Explanation: There is only one '5'. Deleting it leaves "03", and the leading zero is kept.