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[Swift]LeetCode12. 整数转罗马数字 | Integer to Roman

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➤微信公众号：山青咏芝（shanqingyongzhi）
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➤GitHub地址：https://github.com/strengthen/LeetCode
➤原文地址：https://www.cnblogs.com/strengthen/p/9883993.html
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Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Symbol       Value
I             1
V             5
X             10
L             50
C             100
D             500
M             1000

For example, two is written as II in Roman numeral, just two one's added together. Twelve is written as, XII, which is simply X + II. The number twenty seven is written as XXVII, which is XX + V + II.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:

I can be placed before V (5) and X (10) to make 4 and 9.
X can be placed before L (50) and C (100) to make 40 and 90.
C can be placed before D (500) and M (1000) to make 400 and 900.

Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.

Example 1:

Input: 3
Output: "III"

Example 2:

Input: 4
Output: "IV"

Example 3:

Input: 9
Output: "IX"

Example 4:

Input: 58
Output: "LVIII"
Explanation: C = 100, L = 50, XXX = 30 and III = 3.

Example 5:

Input: 1994
Output: "MCMXCIV"
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.

罗马数字包含以下七种字符： I， V， X， L，C，D 和 M。

字符          数值
I             1
V             5
X             10
L             50
C             100
D             500
M             1000

例如，罗马数字 2 写做 II ，即为两个并列的 1。12 写做 XII ，即为 X + II 。 27 写做 XXVII, 即为 XX + V + II 。

通常情况下，罗马数字中小的数字在大的数字的右边。但也存在特例，例如 4 不写做 IIII，而是 IV。数字 1 在数字 5 的左边，所表示的数等于大数 5 减小数 1 得到的数值 4 。同样地，数字 9 表示为 IX。这个特殊的规则只适用于以下六种情况：

I 可以放在 V (5) 和 X (10) 的左边，来表示 4 和 9。
X 可以放在 L (50) 和 C (100) 的左边，来表示 40 和 90。
C 可以放在 D (500) 和 M (1000) 的左边，来表示 400 和 900。

给定一个整数，将其转为罗马数字。输入确保在 1 到 3999 的范围内。

示例 1:

输入: 3
输出: "III"

示例 2:

输入: 4
输出: "IV"

示例 3:

输入: 9
输出: "IX"

示例 4:

输入: 58
输出: "LVIII"
解释: L = 50, V = 5, III = 3.

示例 5:

输入: 1994
输出: "MCMXCIV"
解释: M = 1000, CM = 900, XC = 90, IV = 4.

40ms

 1 class Solution {
 2     func intToRoman(_ num: Int) -> String {
 3         var roman:String = ""
 4         var temp = num
 5         while temp >= 1000 {
 6             roman += "M"
 7             temp = temp - 1000
 8         }
 9         
10         while temp >= 900 {
11             roman += "CM"
12             temp = temp - 900
13         }
14         
15         while temp >= 500 {
16             roman += "D"
17             temp = temp - 500
18         }
19         
20         while temp >= 400 {
21             roman += "CD"
22             temp = temp - 400
23         }
24         
25         while temp >= 100 {
26             roman += "C"
27             temp = temp - 100
28         }
29         
30         while temp >= 90 {
31             roman += "XC"
32             temp = temp - 90
33         }
34         
35         while temp >= 50 {
36             roman += "L"
37             temp = temp - 50
38         }
39         
40         while temp >= 40 {
41             roman += "XL"
42             temp = temp - 40
43         }
44         
45         while temp >= 10 {
46             roman += "X"
47             temp = temp - 10
48         }
49         
50         while temp >= 9 {
51             roman += "IX"
52             temp = temp - 9
53         }
54         
55         while temp >= 5 {
56             roman += "V"
57             temp = temp - 5
58         }
59         
60         while temp >= 4 {
61             roman += "IV"
62             temp = temp - 4
63         }
64         
65         while temp >= 1 {
66             roman += "I"
67             temp = temp - 1
68         }
69         return roman;
70 
71     }
72 }

44ms

 1 class Solution {
 2     func intToRoman(_ num: Int) -> String {
 3         var M:[String] = ["", "M", "MM", "MMM"]
 4         var C:[String] = ["", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"]
 5         var X:[String] = ["", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"]
 6         var I:[String] = ["", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"]
 7  
 8         return M[num/1000] + C[(num%1000)/100] + X[(num%100)/10] + I[num%10];
 9     }
10 }

48ms

 1 class Solution {
 2     
 3     struct romanSt {
 4         var value:Int
 5         var name:String
 6         
 7         init(valueT:Int, nameT:String) {
 8             value = valueT
 9             name = nameT
10         }
11     }
12     
13     func substractPart(_ partValue:romanSt, _ num:Int, _ romanStr:String) ->(value:String, temp:Int) {
14         var roman:String = romanStr
15         var temp = num
16         while temp >= partValue.value {
17             roman += partValue.name
18             temp = temp - partValue.value
19         }
20         return (roman, temp)
21     }
22     
23     let romanStArray:Array<romanSt> = [romanSt(valueT: 1000, nameT: "M"),
24                                        romanSt(valueT: 900, nameT: "CM"),
25                                        romanSt(valueT: 500, nameT: "D"),
26                                        romanSt(valueT: 400, nameT: "CD"),
27                                        romanSt(valueT: 100, nameT: "C"),
28                                        romanSt(valueT: 90, nameT: "XC"),
29                                        romanSt(valueT: 50, nameT: "L"),
30                                        romanSt(valueT: 40, nameT: "XL"),
31                                        romanSt(valueT: 10, nameT: "X"),
32                                        romanSt(valueT: 9, nameT: "IX"),
33                                        romanSt(valueT: 5, nameT: "V"),
34                                        romanSt(valueT: 4, nameT: "IV"),
35                                        romanSt(valueT: 1, nameT: "I")]
36     
37     func intToRoman(_ num: Int) -> String {
38         var roman:String = ""
39         var temp = num
40         
41         for romanSt in romanStArray {
42             (roman, temp) = substractPart(romanSt, temp, roman)
43         }
44         
45         return roman
46     }
47 }

52ms

 1 extension String {
 2     static func *(lhs: String, rhs: Int) -> String {
 3         if rhs < 0 {
 4             return "-(lhs * abs(rhs))"
 5         }
 6         return String(repeating: lhs, count: rhs)
 7     }
 8     
 9     static func +(lhs: String, rhs: String) -> String {
10         if rhs.isEmpty {
11             return lhs
12         } else if rhs[rhs.startIndex] == "-" {
13             return "(rhs[rhs.index(after: rhs.startIndex)...])(lhs)"
14         }
15         return "(lhs)(rhs)"
16     }
17 }
18 
19 enum Roman: String {
20     case I = "I"
21     case V = "V"
22     case X = "X"
23     case L = "L"
24     case C = "C"
25     case D = "D"
26     case M = "M"
27     
28     var val: String {
29         get {
30             return self.rawValue
31         }
32     }
33 }
34 
35 class Solution {
36     private func mapIntToRoman(_ num: Int) -> String {
37         if num < 10 {
38             return num < 4
39                 ? Roman.I.rawValue * num
40                 : (num == 9
41                     ? Roman.I.rawValue + Roman.X.rawValue
42                     : Roman.V.rawValue + Roman.I.rawValue * (num - 5))
43         } else if num < 100 {
44             return num < 40
45                 ? Roman.X.rawValue * (num / 10)
46                 : (num == 90
47                     ? Roman.X.rawValue + Roman.C.rawValue
48                     : Roman.L.rawValue + Roman.X.rawValue * (num / 10 - 5))
49         } else if num < 1000 {
50             return num < 400
51                 ? Roman.C.rawValue * (num / 100)
52                 : (num == 900
53                     ? Roman.C.rawValue + Roman.M.rawValue
54                     : Roman.D.rawValue + Roman.C.rawValue * (num / 100 - 5))
55         } else {
56             return Roman.M.rawValue * (num / 1000)
57         }
58     }
59     
60     func intToRoman(_ num: Int) -> String {
61         var last = num
62         var tens = 1
63         var result = ""
64         
65         while last > 0 {
66             let remain = last % 10 * tens
67             let roman = mapIntToRoman(remain)
68             result = roman + result
69             last = last / 10
70             tens = tens * 10
71         }
72         return result
73     }
74 }

56ms

 1 class Solution {
 2     func intToRoman(_ num: Int) -> String {
 3       var res = ""
 4       var i = num
 5       let dk = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
 6       let d = [1: "I", 5: "V", 10: "X", 50: "L", 100: "C", 500: "D", 1000: "M", 4: "IV", 9: "IX", 40: "XL", 90: "XC", 400: "CD", 900: "CM"]
 7 
 8       while i > 0 {
 9         for div in dk {
10           let kc = i / div
11           guard kc > 0 else { continue }
12           i -= (kc * div)
13           res.append(String(repeating: d[div]!, count: kc))
14         }
15       }
16       return res
17     }
18 }

68ms

 1 class Solution {
 2     func intToRoman(_ num: Int) -> String {
 3         var res = [Character]()
 4         
 5         var num = num
 6         
 7         res += Array(repeating: "M", count: num / 1000)
 8         num = num % 1000
 9         
10         res += digitToRoman(num / 100, [1: "C", 5: "D", 10: "M"])
11         num = num % 100
12         
13         res += digitToRoman(num / 10, [1: "X", 5: "L", 10: "C"])
14         num = num % 10
15         
16         res += digitToRoman(num, [1: "I", 5: "V", 10: "X"])
17         
18         return String(res)
19     }
20     
21     // map[1, 5, 10]
22     func digitToRoman(_ d: Int, _ map: [Int: Character]) -> [Character] {
23         if d <= 3 {
24             return Array(repeating: map[1]!, count: d)
25         } else if d == 4 {
26             return [map[1]!, map[5]!]
27         } else if d < 9 {
28             return [map[5]!] + Array(repeating: map[1]!, count: d-5)
29         } else {
30             return [map[1]!, map[10]!]
31         }
32     }
33 }

72ms

 1 class Solution {
 2     
 3     func intToRoman(_ num: Int) -> String {
 4         let dict = ["I" : 1, "V" : 5, "X" : 10, "L" : 50, "C" : 100, "D" : 500, "M" : 1000]
 5         let symbols = ["M", "D", "C", "L", "X", "V", "I"]
 6         
 7         var result = ""
 8         var divisor = 1000
 9         var index = 0
10         var number = num
11         
12         while divisor > 0 {
13             let quotient = number / divisor
14             if quotient > 0 {
15                 switch quotient {
16                 case 1...3: 
17                     for _ in 0..<quotient {
18                         result += symbols[index]
19                     }
20                 case 4: 
21                     result += symbols[index]
22                     result += symbols[index - 1]
23                 case 5...8:
24                     result += symbols[index - 1]
25                     for _ in 5..<quotient {
26                         result += symbols[index]
27                     }
28                 case 9:
29                     result += symbols[index]
30                     result += symbols[index - 2] 
31                 default:
32                     break
33                 }
34                 number %= divisor
35             }
36             index += 2
37             divisor /= 10
38         }
39         
40         return result
41     }
42 }

72ms

 1 class Solution {
 2     func intToRoman(_ num: Int) -> String {
 3          var tempNum = num;
 4     var ans = ""
 5     
 6     var s = num / 1000
 7     var h = num % 1000 / 100
 8     var t = num % 100 / 10
 9     var g = num % 10
10     
11     while s > 0 {
12         ans += "M"
13         s -= 1
14     }
15     
16     ans += getRoman(h, "C", "D", "M")
17     ans += getRoman(t, "X", "L", "C")
18     ans += getRoman(g, "I", "V", "X")
19     
20     return ans
21     }
22     
23 func getRoman(_ num: Int, _ one: String, _ five: String, _ ten: String) -> String {
24     var ans = ""
25     var tempNum = num;
26     
27     if tempNum == 9 {
28         ans += one + ten
29         tempNum -= 9
30     } else if tempNum >= 5 {
31         ans += five
32         tempNum -= 5
33     } else if tempNum == 4 {
34         ans += one + five
35         tempNum -= 4
36     }
37     
38     while tempNum > 0 {
39         ans += one
40         tempNum -= 1
41     }
42     
43     return ans;
44 }
45 
46 }

80ms

 1 class Solution {
 2     static let digits = [
 3                             ["I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"],
 4                             ["X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"],
 5                             ["C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"], 
 6                             ["M", "MM", "MMM"]
 7                         ]    
 8     
 9     func intToRoman(_ num: Int) -> String {
10         var answer = ""
11         answer.reserveCapacity(15)
12         var i = 3
13         var n = num
14         var p = 1000
15         while i >= 0 {
16             let j = n / p
17             if j != 0 {
18                 answer.append(Solution.digits[i][j - 1])
19             }
20             n = n % p
21             p = p / 10
22             i = i - 1 
23         }
24         return answer
25     }
26 }

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原文地址：https://www.cnblogs.com/strengthen/p/9883993.html