1694. Reformat Phone Number

题目 #

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.

思路1 #

分析 #

  • 自己想的，保留一个数组，如果大于4个，直接拆出前三个加一个-
  • 最后如果剩余4个，拆成22-22，剩余不足4个，直接拼接到后面

代码实现 # 

 1func reformatNumber(number string) (result string) {
 2	var addStr []byte
 3	for i := range number {
 4		if number[i] == ' ' || number[i] == '-' {
 5			continue
 6		}
 7		addStr = append(addStr, number[i])
 8		if len(addStr) > 4 {
 9			result += string(addStr[:3]) + "-"
10			addStr = addStr[3:]
11		}
12	}
13	if len(addStr) == 4 {
14		result += string(addStr[:2]) + "-" + string(addStr[2:])
15	} else {
16		result += string(addStr)
17	}
18	return
19}

思路2 #

分析 #

  • 直接三个三个拼接一个-
  • 最后判断，最后一位是-，删掉
  • 如果倒数第二位是-，和倒数第三位交换值

代码实现 # 

 1func reformatNumber(number string) string {
 2	addStr := make([]byte, 0, 4)
 3	result := make([]byte, 0, len(number))
 4	for i := range number {
 5		if number[i] == ' ' || number[i] == '-' {
 6			continue
 7		}
 8		addStr = append(addStr, number[i])
 9		if len(addStr) == 3 {
10			addStr = append(addStr, '-')
11			result = append(result, addStr...)
12			addStr = addStr[:0]
13		}
14	}
15	result = append(result, addStr...)
16	if result[len(result)-1] == '-' {
17		return string(result[:len(result)-1])
18	} else if len(result) > 4 && result[len(result)-2] == '-' {
19		result[len(result)-2] = result[len(result)-3]
20		result[len(result)-3] = '-'
21	}
22	return string(result)
23}