1694. Reformat Phone Number

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"
Example 5:

Input: number = "--17-5 229 35-39475 "
Output: "175-229-353-94-75"
 

Constraints:

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

这题先把数字给筛选出来，然后根据剩余的数字个数来确定个格式即可。

class ReformatPhoneNumber : public Solution {
public:
    void Exec() {

    }
    string reformatNumber(string number) {
        int count = 0, pop = 0;
        string tmp;
        for (auto c : number) {
            if (c >= '0' && c <= '9') tmp.push_back(c);
        }
        string res;
        while (pop != tmp.size()) {
            if (!res.empty()) {
                res += "-";
            }
            if (tmp.size() - pop > 4) {
                res += tmp.substr(pop, 3);
                pop += 3;
            } else {
                if (tmp.size() - pop == 2) {
                    res += tmp.substr(pop, 2);
                    pop += 2;
                } else if (tmp.size() - pop == 3) {
                    res += tmp.substr(pop, 3);
                    pop += 3;
                } else {
                    res += tmp.substr(pop, 2);
                    res += "-"; pop += 2;
                    res += tmp.substr(pop, 2);
                    pop += 2;
                }
            }
        }
        return res;
    }
};