Reformat Phone Number — LeetCode 1694 Python Solution

The problem

You are given a phone number as a string number. number consists of digits, spaces ' ', and/or dashes '-'.

Example

Input

number = "1-23-45 6"

Output

"123-456"

Explanation

The digits are "123456".

Python solution

class Solution:
    def reformatNumber(self, number: str) -> str:
        number = number.replace("-", "").replace(" ", "")
        n = len(number)
        ans = [number[i * 3 : i * 3 + 3] for i in range(n // 3)]
        if n % 3 == 1:
            ans[-1] = ans[-1][:2]
            ans.append(number[-2:])
        elif n % 3 == 2:
            ans.append(number[-2:])
        return "-".join(ans)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1694. Reformat Phone Number is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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