[Swift]LeetCode166. 分数到小数 | Fraction to Recurring Decimal
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➤微信公众号：山青咏芝（shanqingyongzhi）
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Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.
If the fractional part is repeating, enclose the repeating part in parentheses.
Example 1:
Input: numerator = 1, denominator = 2 Output: "0.5"
Example 2:
Input: numerator = 2, denominator = 1 Output: "2"
Example 3:
Input: numerator = 2, denominator = 3 Output: "0.(6)"
给定两个整数，分别表示分数的分子 numerator 和分母 denominator，以字符串形式返回小数。
如果小数部分为循环小数，则将循环的部分括在括号内。
示例 1:
输入: numerator = 1, denominator = 2 输出: "0.5"
示例 2:
输入: numerator = 2, denominator = 1 输出: "2"
示例 3:
输入: numerator = 2, denominator = 3 输出: "0.(6)"
8ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3 let s1 = numerator > 0 ? 1 : -1
4 let s2 = denominator > 0 ? 1 : -1
5 let numerator = abs(numerator)
6 let denominator = abs(denominator)
7 let num = numerator / denominator
8 var remain = numerator % denominator
9 var remains = [Int : Int]()
10 var res = ""
11 if s1*s2 < 0 && (num > 0 || remain > 0) {
12 res += "-"
13 }
14 res += "\(num)"
15 if remain > 0 {
16 res += "."
17 }
18 var frac = ""
19 var pos = 0
20 while remain > 0 {
21 if let pos = remains[remain] {
22 frac.insert("(", at: frac.index(frac.startIndex, offsetBy: pos))
23 frac += ")"
24 return res+frac
25 }
26 remains[remain] = pos
27 frac += String(remain*10 / denominator)
28 remain = remain*10 % denominator
29 pos += 1
30 }
31 return res+frac
32 }
33 }12ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3
4 if denominator == 0 { return "NaN" }
5
6 //Big bad voodoo magic.
7 var numerator = numerator
8 var denominator = denominator
9
10 //Note, for bools "!=" behaves the same as "^" which is not allowed.
11 var negative = (numerator < 0) != (denominator < 0)
12
13 numerator = abs(numerator)
14 denominator = abs(denominator)
15
16 var result = String(numerator / denominator)
17 var remainder = (numerator % denominator) * 10
18
19 if remainder == 0 {
20 if negative == true && numerator != 0 {
21 return String("-") + result
22 } else {
23 return result
24 }
25 }
26
27 result += "."
28
29 //See if we find repeating digits...
30 //At the point where our long division keeps
31 //dividing into the same NO, we loop 4evz
32 var repeatMap = [Int:Int]()
33
34 while remainder != 0 {
35
36 //We got a repeater? Or nah?
37 if let repeatIndex = repeatMap[remainder] {
38 result.insert("(", at: result.index(result.startIndex, offsetBy: repeatIndex))
39 result += ")"
40 break
41 }
42
43 result += String(remainder / denominator)
44
45 //Set our repeater..
46 repeatMap[remainder] = result.count - 1
47
48 //Perform one more step of long division
49 remainder = (remainder % denominator) * 10
50 }
51
52 if negative == true {
53 return String("-") + result
54 }
55 return result
56 }
57 }12ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3
4 if numerator == 0 {
5 return "0"
6 }
7
8 var res = ""
9
10 if ((numerator < 0) && (denominator >= 0)) || ((numerator >= 0) && (denominator < 0)) {
11 res += "-"
12 }
13
14 let absNum = abs(numerator)
15 let absDen = abs(denominator)
16
17 res += String(absNum/absDen)
18
19 var remander = absNum % absDen
20
21 if remander == 0 {
22 return res
23 }
24
25 res += "."
26
27 var remanders = [Int : Int]()
28
29 var pos = res.count
30
31 var add = 0
32 var hasRecycyle = false
33
34 while remander != 0 && !hasRecycyle {
35 if remanders.keys.contains(remander) {
36 add = remanders[remander]!
37 hasRecycyle = true
38 continue
39 }
40
41 remanders[remander] = pos
42 pos += 1
43 res += String(10 * remander / absDen)
44 remander = (10 * remander) % absDen
45 }
46
47 if hasRecycyle {
48 res.insert("(", at: res.index(res.startIndex, offsetBy: add))
49 res += ")"
50 }
51
52
53 return res
54 }
55 }16ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3 var s1:Int = numerator >= 0 ? 1 : -1
4 var s2:Int = denominator >= 0 ? 1 : -1
5 var num:Int = abs(numerator )
6 var den:Int = abs(denominator )
7 var out:Int = num / den
8 var rem:Int = num % den
9 var m:[Int: Int] = [Int: Int]()
10 var res:String = String(out)
11 if s1 * s2 == -1 && (out > 0 || rem > 0)
12 {
13 res = "-" + res
14 }
15 if rem == 0 {return res}
16 res += "."
17 var s:String = ""
18 var pos:Int = 0
19 while(rem != 0)
20 {
21 if m[rem] != nil
22 {
23 var index = s.index(s.startIndex, offsetBy: m[rem]!)
24 s.insert("(", at:index )
25 s += ")"
26 return res + s
27 }
28 m[rem] = pos
29 s += String((rem * 10) / den)
30 rem = (rem * 10) % den
31 pos += 1
32 }
33 return res + s
34 }
35 }20ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3
4 if numerator % denominator == 0 {
5 return String(numerator/denominator)
6 }
7
8 let n = abs(numerator);
9 let d = abs(denominator);
10
11 var sign = ""
12
13 if numerator > 0 && denominator < 0 || numerator < 0 && denominator > 0{
14 sign = "-"
15 }
16
17 var i = n
18 while i > d {
19 i = i/d
20 }
21
22 var dic = Dictionary<Int, Int>()
23
24 var res = n % d;
25 var s = String()
26
27 var count = 0
28
29 repeat {
30 dic[res] = count
31 res = res * 10;
32 s.append(String(abs(res/d)))
33 res = res % d
34 count = count + 1
35 } while (res != 0 && dic[res] == nil)
36
37 if res == 0 {
38 return sign + String(n/d) + "." + s;
39 }
40 let idx = s.index(s.startIndex, offsetBy: dic[res]!)
41 return sign + String(n/d) + "." + s.substring(to: idx) + "(" + s.substring(from: idx) + ")"
42 }
43 }20ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3 let r = numerator % denominator
4 let k = numerator / denominator
5 if r == 0 {
6 return "\(k)"
7 }
8
9 let tail = helper(abs(r), abs(denominator))
10 var ret = "\(abs(k)).\(tail)"
11 if numerator * denominator < 0 {
12 ret = "-" + ret
13 }
14 return ret
15 }
16
17
18 func helper(_ n: Int, _ m: Int) -> String {
19 var ret = ""
20 var map = [Int: Int]()
21 var x = n
22 while x != 0 {
23 if let i = map[x] {
24 ret = ret.prefix(i) + "(" + ret.suffix(ret.count - i) + ")"
25 return ret
26 }
27 let y = x * 10
28 let k = y / m
29 map[x] = ret.count
30 ret += "\(k)"
31 x = y % m
32 }
33 return ret
34 }
35 }36ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3 if denominator == 0 {
4 return ""
5 }
6
7 if numerator == 0 {
8 return "0"
9 }
10
11 //取绝对值
12 var num1 = numerator > 0 ? numerator : -numerator
13 let num2 = denominator > 0 ? denominator : -denominator
14 //取方向
15 var result = (numerator > 0 && denominator < 0) || (numerator < 0 && denominator > 0) ? "-" : ""
16
17 //整数部分
18 result += String(num1/num2)
19 num1 = num1 % num2
20 if num1 == 0 {
21 return result
22 }else {
23 result += "."
24 }
25
26 //小数部分
27 var dic = [Int:Int]()
28
29 while num1 != 0 {
30 if dic.keys.contains(num1) {
31 let index = result.index(result.startIndex, offsetBy: dic[num1]!)
32 result.insert("(", at: index)
33 result += ")"
34 break
35 }
36 dic[num1] = result.count
37 num1 *= 10
38 result += String(num1/num2)
39 num1 %= num2
40 }
41 return result
42 }
43 }56ms
1 class Solution {
2 func fractionToDecimal(_ numerator: Int, _ denominator: Int) -> String {
3 if numerator == 0 { return "0" }
4 let sign = (numerator > 0 ? 1 : -1) ^ (denominator > 0 ? 1 : -1) == 0 ? "" : "-"
5 var result = sign
6 var a = abs(numerator)
7 let b = abs(denominator)
8 result += "\(a/b)"
9 a = a % b
10 if a != 0 {
11 result += "."
12 } else {
13 return result
14 }
15 var decimal = ""
16 var array = [a]
17 while true {
18 a = a * 10
19 decimal += "\(a/b)"
20 a = a % b
21 if a == 0 {
22 result += decimal
23 return result
24 }
25 if let index = array.index(of: a) {
26 var temp = [Character](decimal)
27 temp.insert("(", at: index)
28 temp.append(")")
29 result += String(temp)
30 return result
31 } else {
32 array.append(a)
33 }
34 }
35 }
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