leetcode401二进制表
- 题目描述
- 解题思路
- 执行结果
题目描述
**二进制手表顶部有 4 个 LED 代表 小时（0-11），底部的 6 个 LED 代表 分钟（0-59）。每个 LED 代表一个 0 或 1，最低位在右侧。
例如，下面的二进制手表读取 "3:25" 。
（图源：WikiMedia - Binary clock samui moon.jpg ，许可协议：Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) ）
给你一个整数 turnedOn ，表示当前亮着的 LED 的数量，返回二进制手表可以表示的所有可能时间。你可以 按任意顺序 返回答案。
小时不会以零开头：
例如，"01:00" 是无效的时间，正确的写法应该是 "1:00" 。 分钟必须由两位数组成，可能会以零开头：
例如，"10:2" 是无效的时间，正确的写法应该是 "10:02" 。
示例 1：
输入：turnedOn = 1 输出：["0:01","0:02","0:04","0:08","0:16","0:32","1:00","2:00","4:00","8:00"] 示例 2：
输入：turnedOn = 9 输出：[]
提示：
0 <= turnedOn <= 10
来源：力扣（LeetCode） 链接：https://leetcode.cn/problems/binary-watch 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。**
解题思路
法1
所有用例:
简单因为用例只有10个,10种情况做成swich,case语句中 return就行了
func readBinaryWatch(turnedOn int) []string {
switch turnedOn {
case 1:
return []string{"0:01", "0:02", "0:04", "0:08", "0:16", "0:32", "1:00", "2:00", "4:00", "8:00"}
case 2:
return []string{"0:03","0:05","0:06","0:09","0:10","0:12","0:17","0:18","0:20","0:24","0:33","0:34","0:36","0:40","0:48","1:01","1:02","1:04","1:08","1:16","1:32","2:01","2:02","2:04","2:08","2:16","2:32","3:00","4:01","4:02","4:04","4:08","4:16","4:32","5:00","6:00","8:01","8:02","8:04","8:08","8:16","8:32","9:00","10:00"}
case 3:
return []string{"0:07","0:11","0:13","0:14","0:19","0:21","0:22","0:25","0:26","0:28","0:35","0:37","0:38","0:41","0:42","0:44","0:49","0:50","0:52","0:56","1:03","1:05","1:06","1:09","1:10","1:12","1:17","1:18","1:20","1:24","1:33","1:34","1:36","1:40","1:48","2:03","2:05","2:06","2:09","2:10","2:12","2:17","2:18","2:20","2:24","2:33","2:34","2:36","2:40","2:48","3:01","3:02","3:04","3:08","3:16","3:32","4:03","4:05","4:06","4:09","4:10","4:12","4:17","4:18","4:20","4:24","4:33","4:34","4:36","4:40","4:48","5:01","5:02","5:04","5:08","5:16","5:32","6:01","6:02","6:04","6:08","6:16","6:32","7:00","8:03","8:05","8:06","8:09","8:10","8:12","8:17","8:18","8:20","8:24","8:33","8:34","8:36","8:40","8:48","9:01","9:02","9:04","9:08","9:16","9:32","10:01","10:02","10:04","10:08","10:16","10:32","11:00"}
case 4:
return []string{"0:15","0:23","0:27","0:29","0:30","0:39","0:43","0:45","0:46","0:51","0:53","0:54","0:57","0:58","1:07","1:11","1:13","1:14","1:19","1:21","1:22","1:25","1:26","1:28","1:35","1:37","1:38","1:41","1:42","1:44","1:49","1:50","1:52","1:56","2:07","2:11","2:13","2:14","2:19","2:21","2:22","2:25","2:26","2:28","2:35","2:37","2:38","2:41","2:42","2:44","2:49","2:50","2:52","2:56","3:03","3:05","3:06","3:09","3:10","3:12","3:17","3:18","3:20","3:24","3:33","3:34","3:36","3:40","3:48","4:07","4:11","4:13","4:14","4:19","4:21","4:22","4:25","4:26","4:28","4:35","4:37","4:38","4:41","4:42","4:44","4:49","4:50","4:52","4:56","5:03","5:05","5:06","5:09","5:10","5:12","5:17","5:18","5:20","5:24","5:33","5:34","5:36","5:40","5:48","6:03","6:05","6:06","6:09","6:10","6:12","6:17","6:18","6:20","6:24","6:33","6:34","6:36","6:40","6:48","7:01","7:02","7:04","7:08","7:16","7:32","8:07","8:11","8:13","8:14","8:19","8:21","8:22","8:25","8:26","8:28","8:35","8:37","8:38","8:41","8:42","8:44","8:49","8:50","8:52","8:56","9:03","9:05","9:06","9:09","9:10","9:12","9:17","9:18","9:20","9:24","9:33","9:34","9:36","9:40","9:48","10:03","10:05","10:06","10:09","10:10","10:12","10:17","10:18","10:20","10:24","10:33","10:34","10:36","10:40","10:48","11:01","11:02","11:04","11:08","11:16","11:32"}
case 5:
return []string{"0:31","0:47","0:55","0:59","1:15","1:23","1:27","1:29","1:30","1:39","1:43","1:45","1:46","1:51","1:53","1:54","1:57","1:58","2:15","2:23","2:27","2:29","2:30","2:39","2:43","2:45","2:46","2:51","2:53","2:54","2:57","2:58","3:07","3:11","3:13","3:14","3:19","3:21","3:22","3:25","3:26","3:28","3:35","3:37","3:38","3:41","3:42","3:44","3:49","3:50","3:52","3:56","4:15","4:23","4:27","4:29","4:30","4:39","4:43","4:45","4:46","4:51","4:53","4:54","4:57","4:58","5:07","5:11","5:13","5:14","5:19","5:21","5:22","5:25","5:26","5:28","5:35","5:37","5:38","5:41","5:42","5:44","5:49","5:50","5:52","5:56","6:07","6:11","6:13","6:14","6:19","6:21","6:22","6:25","6:26","6:28","6:35","6:37","6:38","6:41","6:42","6:44","6:49","6:50","6:52","6:56","7:03","7:05","7:06","7:09","7:10","7:12","7:17","7:18","7:20","7:24","7:33","7:34","7:36","7:40","7:48","8:15","8:23","8:27","8:29","8:30","8:39","8:43","8:45","8:46","8:51","8:53","8:54","8:57","8:58","9:07","9:11","9:13","9:14","9:19","9:21","9:22","9:25","9:26","9:28","9:35","9:37","9:38","9:41","9:42","9:44","9:49","9:50","9:52","9:56","10:07","10:11","10:13","10:14","10:19","10:21","10:22","10:25","10:26","10:28","10:35","10:37","10:38","10:41","10:42","10:44","10:49","10:50","10:52","10:56","11:03","11:05","11:06","11:09","11:10","11:12","11:17","11:18","11:20","11:24","11:33","11:34","11:36","11:40","11:48"}
case 6:
return []string{"1:31","1:47","1:55","1:59","2:31","2:47","2:55","2:59","3:15","3:23","3:27","3:29","3:30","3:39","3:43","3:45","3:46","3:51","3:53","3:54","3:57","3:58","4:31","4:47","4:55","4:59","5:15","5:23","5:27","5:29","5:30","5:39","5:43","5:45","5:46","5:51","5:53","5:54","5:57","5:58","6:15","6:23","6:27","6:29","6:30","6:39","6:43","6:45","6:46","6:51","6:53","6:54","6:57","6:58","7:07","7:11","7:13","7:14","7:19","7:21","7:22","7:25","7:26","7:28","7:35","7:37","7:38","7:41","7:42","7:44","7:49","7:50","7:52","7:56","8:31","8:47","8:55","8:59","9:15","9:23","9:27","9:29","9:30","9:39","9:43","9:45","9:46","9:51","9:53","9:54","9:57","9:58","10:15","10:23","10:27","10:29","10:30","10:39","10:43","10:45","10:46","10:51","10:53","10:54","10:57","10:58","11:07","11:11","11:13","11:14","11:19","11:21","11:22","11:25","11:26","11:28","11:35","11:37","11:38","11:41","11:42","11:44","11:49","11:50","11:52","11:56"}
case 7:
return []string{"3:31","3:47","3:55","3:59","5:31","5:47","5:55","5:59","6:31","6:47","6:55","6:59","7:15","7:23","7:27","7:29","7:30","7:39","7:43","7:45","7:46","7:51","7:53","7:54","7:57","7:58","9:31","9:47","9:55","9:59","10:31","10:47","10:55","10:59","11:15","11:23","11:27","11:29","11:30","11:39","11:43","11:45","11:46","11:51","11:53","11:54","11:57","11:58"}
case 8:
return []string{"7:31","7:47","7:55","7:59","11:31","11:47","11:55","11:59"}
case 0:
return []string{"0:00"}
}
return nil
}
- 时间复杂度O(1)
- 空间复杂度O(1)
因为代码中没有使用任何额外的数据结构或内存分配。函数只是返回一些字符串，它们在代码中已经硬编码，因此它们被存储在代码段中，不需要额外的内存分配。此外，该函数的输入参数也没有在堆栈中分配内存，而是使用寄存器传递。因此，该函数的空间复杂度是常量级别的。
法2
枚举:亮灯的个数=1的个数=小时的个数+分钟的个数
思路:二进制1的个数:要知道只有亮的时候是1,也就是个数n=小时1的个数+分钟1的个数\
- 如果小时的个数加分钟的个数==提供的个数,就可以加入\
前提:小时<12,分钟<60
//核心判断
if bits.OnesCount8(h)+bits.OnesCount8(min) == turnedOn {
a = append(a, fmt.Sprintf("%d:%02d", h, min))
}
时间复杂度O(1)
空间复杂度O(1)
代码相比之下要清洁很多
执行结果
法1
func readBinaryWatch(turnedOn int) []string {
switch turnedOn {//switch所有的情况,9,与10都返回nil
case 1:
return []string{"0:01", "0:02", "0:04", "0:08", "0:16", "0:32", "1:00", "2:00", "4:00", "8:00"}
case 2:
return []string{"0:03","0:05","0:06","0:09","0:10","0:12","0:17","0:18","0:20","0:24","0:33","0:34","0:36","0:40","0:48","1:01","1:02","1:04","1:08","1:16","1:32","2:01","2:02","2:04","2:08","2:16","2:32","3:00","4:01","4:02","4:04","4:08","4:16","4:32","5:00","6:00","8:01","8:02","8:04","8:08","8:16","8:32","9:00","10:00"}
case 3:
return []string{"0:07","0:11","0:13","0:14","0:19","0:21","0:22","0:25","0:26","0:28","0:35","0:37","0:38","0:41","0:42","0:44","0:49","0:50","0:52","0:56","1:03","1:05","1:06","1:09","1:10","1:12","1:17","1:18","1:20","1:24","1:33","1:34","1:36","1:40","1:48","2:03","2:05","2:06","2:09","2:10","2:12","2:17","2:18","2:20","2:24","2:33","2:34","2:36","2:40","2:48","3:01","3:02","3:04","3:08","3:16","3:32","4:03","4:05","4:06","4:09","4:10","4:12","4:17","4:18","4:20","4:24","4:33","4:34","4:36","4:40","4:48","5:01","5:02","5:04","5:08","5:16","5:32","6:01","6:02","6:04","6:08","6:16","6:32","7:00","8:03","8:05","8:06","8:09","8:10","8:12","8:17","8:18","8:20","8:24","8:33","8:34","8:36","8:40","8:48","9:01","9:02","9:04","9:08","9:16","9:32","10:01","10:02","10:04","10:08","10:16","10:32","11:00"}
case 4:
return []string{"0:15","0:23","0:27","0:29","0:30","0:39","0:43","0:45","0:46","0:51","0:53","0:54","0:57","0:58","1:07","1:11","1:13","1:14","1:19","1:21","1:22","1:25","1:26","1:28","1:35","1:37","1:38","1:41","1:42","1:44","1:49","1:50","1:52","1:56","2:07","2:11","2:13","2:14","2:19","2:21","2:22","2:25","2:26","2:28","2:35","2:37","2:38","2:41","2:42","2:44","2:49","2:50","2:52","2:56","3:03","3:05","3:06","3:09","3:10","3:12","3:17","3:18","3:20","3:24","3:33","3:34","3:36","3:40","3:48","4:07","4:11","4:13","4:14","4:19","4:21","4:22","4:25","4:26","4:28","4:35","4:37","4:38","4:41","4:42","4:44","4:49","4:50","4:52","4:56","5:03","5:05","5:06","5:09","5:10","5:12","5:17","5:18","5:20","5:24","5:33","5:34","5:36","5:40","5:48","6:03","6:05","6:06","6:09","6:10","6:12","6:17","6:18","6:20","6:24","6:33","6:34","6:36","6:40","6:48","7:01","7:02","7:04","7:08","7:16","7:32","8:07","8:11","8:13","8:14","8:19","8:21","8:22","8:25","8:26","8:28","8:35","8:37","8:38","8:41","8:42","8:44","8:49","8:50","8:52","8:56","9:03","9:05","9:06","9:09","9:10","9:12","9:17","9:18","9:20","9:24","9:33","9:34","9:36","9:40","9:48","10:03","10:05","10:06","10:09","10:10","10:12","10:17","10:18","10:20","10:24","10:33","10:34","10:36","10:40","10:48","11:01","11:02","11:04","11:08","11:16","11:32"}
case 5:
return []string{"0:31","0:47","0:55","0:59","1:15","1:23","1:27","1:29","1:30","1:39","1:43","1:45","1:46","1:51","1:53","1:54","1:57","1:58","2:15","2:23","2:27","2:29","2:30","2:39","2:43","2:45","2:46","2:51","2:53","2:54","2:57","2:58","3:07","3:11","3:13","3:14","3:19","3:21","3:22","3:25","3:26","3:28","3:35","3:37","3:38","3:41","3:42","3:44","3:49","3:50","3:52","3:56","4:15","4:23","4:27","4:29","4:30","4:39","4:43","4:45","4:46","4:51","4:53","4:54","4:57","4:58","5:07","5:11","5:13","5:14","5:19","5:21","5:22","5:25","5:26","5:28","5:35","5:37","5:38","5:41","5:42","5:44","5:49","5:50","5:52","5:56","6:07","6:11","6:13","6:14","6:19","6:21","6:22","6:25","6:26","6:28","6:35","6:37","6:38","6:41","6:42","6:44","6:49","6:50","6:52","6:56","7:03","7:05","7:06","7:09","7:10","7:12","7:17","7:18","7:20","7:24","7:33","7:34","7:36","7:40","7:48","8:15","8:23","8:27","8:29","8:30","8:39","8:43","8:45","8:46","8:51","8:53","8:54","8:57","8:58","9:07","9:11","9:13","9:14","9:19","9:21","9:22","9:25","9:26","9:28","9:35","9:37","9:38","9:41","9:42","9:44","9:49","9:50","9:52","9:56","10:07","10:11","10:13","10:14","10:19","10:21","10:22","10:25","10:26","10:28","10:35","10:37","10:38","10:41","10:42","10:44","10:49","10:50","10:52","10:56","11:03","11:05","11:06","11:09","11:10","11:12","11:17","11:18","11:20","11:24","11:33","11:34","11:36","11:40","11:48"}
case 6:
return []string{"1:31","1:47","1:55","1:59","2:31","2:47","2:55","2:59","3:15","3:23","3:27","3:29","3:30","3:39","3:43","3:45","3:46","3:51","3:53","3:54","3:57","3:58","4:31","4:47","4:55","4:59","5:15","5:23","5:27","5:29","5:30","5:39","5:43","5:45","5:46","5:51","5:53","5:54","5:57","5:58","6:15","6:23","6:27","6:29","6:30","6:39","6:43","6:45","6:46","6:51","6:53","6:54","6:57","6:58","7:07","7:11","7:13","7:14","7:19","7:21","7:22","7:25","7:26","7:28","7:35","7:37","7:38","7:41","7:42","7:44","7:49","7:50","7:52","7:56","8:31","8:47","8:55","8:59","9:15","9:23","9:27","9:29","9:30","9:39","9:43","9:45","9:46","9:51","9:53","9:54","9:57","9:58","10:15","10:23","10:27","10:29","10:30","10:39","10:43","10:45","10:46","10:51","10:53","10:54","10:57","10:58","11:07","11:11","11:13","11:14","11:19","11:21","11:22","11:25","11:26","11:28","11:35","11:37","11:38","11:41","11:42","11:44","11:49","11:50","11:52","11:56"}
case 7:
return []string{"3:31","3:47","3:55","3:59","5:31","5:47","5:55","5:59","6:31","6:47","6:55","6:59","7:15","7:23","7:27","7:29","7:30","7:39","7:43","7:45","7:46","7:51","7:53","7:54","7:57","7:58","9:31","9:47","9:55","9:59","10:31","10:47","10:55","10:59","11:15","11:23","11:27","11:29","11:30","11:39","11:43","11:45","11:46","11:51","11:53","11:54","11:57","11:58"}
case 8:
return []string{"7:31","7:47","7:55","7:59","11:31","11:47","11:55","11:59"}
case 0:
return []string{"0:00"}
}
return nil
}
执行用时： 0 ms , 在所有 Go 提交中击败了 100.00% 的用户 内存消耗： 1.9 MB , 在所有 Go 提交中击败了 59.72% 的用户 通过测试用例： 11 / 11
法2
// 二进制1的个数:要知道只有亮的时候是1,也就是个数n=小时1的个数+分钟1的个数
func readBinaryWatch(turnedOn int) []string {
a := []string{}
for h := uint8(0); h < 12; {
for min := uint8(0); min < 12; {
if bits.OnesCount8(h)+bits.OnesCount8(min) == turnedOn {
a = append(a, fmt.Sprintf("%d:%02d", h, min))
}
}
}
return a
}
执行结果： 通过 显示详情 查看示例代码 添加备注
执行用时： 0 ms , 在所有 Go 提交中击败了 100.00% 的用户 内存消耗： 1.9 MB , 在所有 Go 提交中击败了 45.83% 的用户 通过测试用例： 11 / 11
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