# [LeetCode]#1694. Reformat Phone Number

**Environment: Python 3.8**

**Key technique: join, split, while**

You are given a phone number as a string `number`

. `number`

consists of digits, spaces `' '`

, and/or dashes `'-'`

.

You would like to reformat the phone number in a certain manner. Firstly, **remove** all spaces and dashes. Then, **group** the digits from left to right into blocks of length 3 **until** there are 4 or fewer digits. The final digits are then grouped as follows:

- 2 digits: A single block of length 2.
- 3 digits: A single block of length 3.
- 4 digits: Two blocks of length 2 each.

The blocks are then joined by dashes. Notice that the reformatting process should **never** produce any blocks of length 1 and produce **at most** two blocks of length 2.

Return *the phone number after formatting.*

**Example 1:**

**Input:** number = "1-23-45 6"

**Output:** "123-456"

**Explanation:** The digits are "123456".

Step 1: There are more than 4 digits, so group the next 3 digits. The 1st block is "123".

Step 2: There are 3 digits remaining, so put them in a single block of length 3. The 2nd block is "456".

Joining the blocks gives "123-456".

**Example 2:**

**Input:** number = "123 4-567"

**Output:** "123-45-67"

**Explanation: **The digits are "1234567".

Step 1: There are more than 4 digits, so group the next 3 digits. The 1st block is "123".

Step 2: There are 4 digits left, so split them into two blocks of length 2. The blocks are "45" and "67".

Joining the blocks gives "123-45-67".

**Example 3:**

**Input:** number = "123 4-5678"

**Output:** "123-456-78"

**Explanation:** The digits are "12345678".

Step 1: The 1st block is "123".

Step 2: The 2nd block is "456".

Step 3: There are 2 digits left, so put them in a single block of length 2. The 3rd block is "78".

Joining the blocks gives "123-456-78".

**Example 4:**

**Input:** number = "12"

**Output:** "12

**Analysis:**

- number=”123 4–5678"
- replace “-” with “”
- replace “ “ with “”
- if n size >3, 123-. left number is 45678
- if n size >3, 123–456-. Left number is 78
- Return 123–456–78

**Solution:**

`class Solution:`

def reformatNumber(self, number):

n = "".join(number.split("-"))

n="".join(n.split(" "))

ans = ''

while len(n) > 4:

ans += n[:3] + '-'

n = n[3:]

if len(n) == 4:

ans += n[:2] + '-' + n[2:]

else:

ans += n

return ans

**Submissions:**

**Reference:**