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
numberconsists of digits and the characters'-'and' '.- There are at least two digits in
number.
Solution
思路：特判长度，如果模 3 余 1 说明最后会剩 1 个数字，将最后的四个数字特殊处理。其他情况直接三个字母加 - 即可
C
char * reformatNumber(char * number){
int i, len_number, len_digit, len_ans, n;
char digit[101];
char *ans = (char*)malloc(sizeof(char) * 1000);
len_number = strlen(number);
len_digit = 0;
len_ans = 0;
for (i = 0; i < len_number; i++) {
if (number[i] >= '0' && number[i] <= '9') {
digit[len_digit++] = number[i];
}
}
if (len_digit % 3 == 1) {
n = len_digit - 4;
} else {
n = len_digit;
}
for (i = 0; i < n; i++) {
ans[len_ans++] = digit[i];
if (i != 0 && i != len_digit - 1 && i % 3 == 2) {
ans[len_ans++] = '-';
}
}
if (len_digit % 3 == 1) {
ans[len_ans++] = digit[i++];
ans[len_ans++] = digit[i++];
ans[len_ans++] = '-';
ans[len_ans++] = digit[i++];
ans[len_ans++] = digit[i++];
}
ans[len_ans++] = '\0';
return ans;
}
Python3
class Solution:
def reformatNumber(self, number: str) -> str:
digit = []
for ch in number:
if ch.isdigit():
digit.append(ch)
n = len(digit)
ans = []
if n % 3 == 1:
for i in range(0, n - 4, 3):
ans.append("".join(digit[i : i + 3]))
ans.append("".join(digit[-4 : -2]))
ans.append("".join(digit[-2 : -1]) + digit[-1])
else:
for i in range(0, n, 3):
ans.append("".join(digit[i : i + 3]))
return "-".join(ans)
