[Swift]LeetCode401.二进制手表|BinaryWatch

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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.

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，上面的二进制手表读取 “3:25”。

给定一个非负整数 n 代表当前 LED 亮着的数量，返回所有可能的时间。

案例:

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

注意事项:

输出的顺序没有要求。
小时不会以零开头，比如 “01:00” 是不允许的，应为 “1:00”。
分钟必须由两位数组成，可能会以零开头，比如 “10:2” 是无效的，应为 “10:02”。

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3         var times:[String] = [String]()   
 4         //轮询遍历
 5         for h in 0..<12
 6         {
 7             //将常量转换为变量
 8             var hour:Int = h
 9             for m in 0..<60
10             {
11                 //将常量转换为变量
12                 var minute:Int = m
13                 var number:Int = hour*64 + minute
14                 if number.bitCount() == num
15                 {
16                     //minute不足2位前面补0的写法：%02d
17                     var str = String(format: "%d:%02d", arguments:[hour,minute]) 
18                     times.append(str)
19                 }
20             }           
21         }
22         return times
23     }   
24 }
25 //Int扩展代码
26 extension Int
27 {
28     mutating func bitCount() -> Int
29     {
30         self = self - ((self >> 1) & 0x55555555);
31         self = (self & 0x33333333) + ((self >> 2) & 0x33333333);
32         self = (self + (self >> 4)) & 0x0f0f0f0f;
33         self = self + (self >> 8);
34         self = self + (self >> 16);
35         return self & 0x3f;        
36     }
37 }

8ms

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3        
 4         let leds = [1, 2, 4, 8, 1, 2, 4, 8, 16, 32]
 5         var result = [String]()
 6         readBinaryWatch(leds, leds.count, 0, (leds.count - num), 0, 0, &result) 
 7         return result
 8     } 
 9     
10     func readBinaryWatch(_ leds: [Int], _ ledsCount: Int, _ left: Int, _ right: Int, _ hours: Int, _ minutes: Int, _ result: inout [String]) {
11         if hours > 11 || minutes > 59 { return }
12         if right >= leds.count {
13             result.append(String(format: "%d:%02d", hours, minutes)) 
14             return 
15         }
16         
17         for index in left...right {
18             var currentHours = hours
19             var currentMinutes = minutes
20             
21             let value = leds[index]
22             if index >= 4 { currentMinutes += value } 
23             else { currentHours += value } 
24             
25             readBinaryWatch(leds, ledsCount, index + 1, right + 1, currentHours, currentMinutes, &result)  
26         }
27     }
28     
29 }

12ms

 1 class Solution {
 2     let hourArray = [
 3         [0],
 4         [1, 2, 4, 8],
 5         [3, 5, 6, 9, 10],
 6         [7, 11]
 7     ]
 8     let minArray = [
 9         [0],
10         [1, 2, 4, 8, 16, 32],
11         [3, 5, 6, 9, 10, 12, 17, 18, 20, 24, 33, 34, 36, 40, 48],
12         [7, 11, 13, 14, 19, 21, 22, 25, 26, 28, 35, 37, 38, 41, 42, 44, 49, 50, 52, 56],
13         [15, 23, 27, 29, 30, 39, 43, 45, 46, 51, 53, 54, 57, 58],
14         [31, 47, 55, 59]
15     ]
16     func readBinaryWatch(_ num: Int) -> [String] {
17         var result = [String]()
18         
19         for hNum in 0...min(3, num) {
20             let mNum = num - hNum
21             if mNum < minArray.count {
22                 for h in hourArray[hNum] {
23                     for m in minArray[mNum] {
24                         result.append("\(h):\(String(format: "%02d", m))")
25                     }
26                 }
27             }
28         }
29         return result
30     }
31 }

20ms

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3         var times: [String] = []
 4         let maxClock = num == 1 ? 8 : 11
 5         let maxMinute = num == 1 ? 32 : 59
 6         for clock in 0...maxClock {
 7             for minute in 0...maxMinute {
 8                 if bitCount(clock) + bitCount(minute) == num {
 9                     let time = String(format: "%d:%02d", clock, minute)
10                     times.append(time)
11                 }
12             }
13         }
14         
15         return times
16     }
17     
18     func bitCount(_ num: Int) -> Int {
19         var result = 0
20         var num2 = num
21         while num2 > 0 {
22             result += num2 & 1
23             num2 >>= 1
24         }
25         
26         return result
27     }
28 }

28ms

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3         var res = [String]()
 4 
 5         func bitCount(_ num: Int) -> Int {
 6             var count = 0
 7             var num = num
 8             while num > 0 {
 9                 count += num & 1
10                 num >>= 1
11             }
12             return count
13         }
14 
15         for h in 0...11 {
16             for m in 0...59 {
17                 if bitCount(h) + bitCount(m) == num {
18                     res.append(String(format: "%d:%02d", h, m))
19                 }
20             }
21         }
22 
23         return res
24     }
25 }

48ms

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3         var ret: [String] = []
 4         
 5         for i in 0...11 {
 6             for j in 0...59 {
 7                 let hourBinary = String(i, radix: 2).filter { $0 == "1" }
 8                 let minuteBinary = String(j, radix: 2).filter { $0 == "1" }
 9                 
10                 if hourBinary.count + minuteBinary.count == num {
11                     ret.append(String(format: "%d:%02d", i, j))
12                 }
13             }
14         }
15         
16         return ret
17     }
18 }

48ms

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3         var res = [String]()
 4 
 5         func findLEDs(_ h: Int, _ m: Int) -> Int {
 6             let hc = Array(String(h, radix: 2)).filter { $0 == "1" }.count
 7             let mc = Array(String(m, radix: 2)).filter { $0 == "1" }.count
 8             return hc + mc
 9         }
10 
11         for h in 0...11 {
12             for m in 0...59 {
13                 if findLEDs(h, m) == num {
14                     res.append(String(format: "%d:%02d", h, m))
15                 }
16             }
17         }
18 
19         return res
20     }
21 }

52ms

 1 class Solution {
 2     func readBinaryWatch(_ num: Int) -> [String] {
 3     var result = [String]()
 4     
 5     func findLEDs(_ h: Int, _ m: Int) -> Int {
 6         let hc = Array(String(h, radix: 2).characters).filter { $0 == "1" }.count
 7         let mc = Array(String(m, radix: 2).characters).filter { $0 == "1" }.count
 8         return hc + mc
 9     }
10     for h in 0...11 {
11         for m in 0...59 {
12             if findLEDs(h, m) == num {
13                 result.append(String(format: "%d:%02d", h, m))
14             }
15         }
16     }
17     return result
18     }
19 }