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401. 二进制手表 Binary Watch

2024-08-31 14:34:28   209人阅读

A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59).

Each LED represents a zero or one, with the least significant bit on the right.

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For example, the above binary watch reads "3:25".

Given a non-negative integer n which represents the number of LEDs that are currently on, return all possible times the watch could represent.

Example:

Input: n = 1
Return: ["1:00", "2:00", "4:00", "8:00", "0:01", "0:02", "0:04", "0:08", "0:16", "0:32"]

Note:

  • The order of output does not matter.
  • The hour must not contain a leading zero, for example "01:00" is not valid, it should be "1:00".
  • The minute must be consist of two digits and may contain a leading zero, for example "10:2" is not valid, it should be "10:02".

二进制手表上的数字有一个特点：转换成二进制后，只有1位的数字为1
例如： 2=10
            4=100
            8=1000
可以利用这一特性进行解题
  1. static public List<string> ReadBinaryWatch(int num) {
  2. 	List<string> list = new List<string>();
  3. 	string s = "";
  4. 	for (int i = 0; i < 12; i++) {
  5. 		for (int j = 0; j < 60; j++) {
  6. 			if (BitCount(i) + BitCount(j) == num) {
  7. 				list.Add(i.ToString() + ":" + NumberToString(j));
  8. 			}
  9. 		}
  10. 	}
  11. 	return list;
  12. }
  14. static public int BitCount(int number) {
  15. 	int sum = 0;
  16. 	while (number > 0) {
  17. 		if ((number & 1) == 1) {
  18. 			sum++;
  19. 		}
  20. 		number >>= 1;
  21. 	}
  22. 	return sum;
  23. }
  25. static public string NumberToString(int number) {
  26. 	string s = number.ToString();
  27. 	return s.PadLeft(2, ‘0‘);
  28. }



来自为知笔记(Wiz)


401. 二进制手表 Binary Watch


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