1694. Reformat Phone Number

QUESTION:

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".

Constraints:

2 <= number.length <= 100
number consists of digits and the characters '-' and ' '.
There are at least two digits in number.

EXPLANATION:

只要按照题目要求的进行模拟出来即可.

SOLUTION:

class Solution {
    func reformatNumber(_ number: String) -> String {
        var arr:Array<Character> = []
        for num in number {
            if (num >= "0" && num <= "9") {
                arr.append(num)
            }
        }
        var index = 0
        var result = ""
        while (index < arr.count) {
            if (arr.count - index > 4) {
                for _ in 1...3 {
                    result += String(arr[index])
                    index += 1
                }
                result += "-"
            } else if (arr.count - index == 4) {
                for _ in 1...2 {
                    result += String(arr[index])
                    index += 1
                }
                result += "-"
                for _ in 1...2 {
                    result += String(arr[index])
                    index += 1
                }
            } else if (arr.count - index == 3) {
                for _ in 1...3 {
                    result += String(arr[index])
                    index += 1
                }
            } else {
                for _ in 1...2 {
                    result += String(arr[index])
                    index += 1
                }
            }
        }
        return result
    }
}
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