[Swift]LeetCode504. 七进制数 | Base 7

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Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

 Example 2:

Input: -7
Output: "-10"

 Note: The input will be in range of [-1e7, 1e7].

---

 给定一个整数，将其转化为7进制，并以字符串形式输出。

示例 1:

输入: 100
输出: "202"

示例 2:

输入: -7
输出: "-10"

注意: 输入范围是 [-1e7, 1e7] 。

---

 16ms

class Solution {
    func convertToBase7(_ num: Int) -> String {
        if num == 0 {return "0"}
        var res:[Int] = [Int]()
        //取绝对值
        var number:Int = abs(num)
        while(number != 0)
        {
            var temp:Int = number % 7
            number /= 7
            //在位置0处插入
            res.insert(temp,at: 0)
        }
        //数组转字符串
        let dataInt = res.map(String.init)      
        var str:String = dataInt.joined(separator: "")
        if num < 0
        {
            str = "-" + str
        }
        return str
    }
}

---

8ms

class Solution {
    func convertToBase7(_ num: Int) -> String {
        var input = abs(num)

        var result = ""

        if num == 0 {
            return "0"
        }

        while input >= 1 {
            result = "\(input % 7)" + result
            input = input / 7
        }

        if num < 0 {
            result = "-" + result
        }

        return result
    }
}

---

12ms

class Solution {
    func convertToBase7(_ num: Int) -> String {
        if num == 0 { return "0" }
        let number = abs(num)
        var result = ""
        var x = number
        while x > 0 {
            let rem = x % 7
            result = "\(rem)\(result)"
            x = x / 7
        }
        
        return num < 0 ? "-\(result)" : result
    }
}

---

20ms

class Solution {
    func convertToBase7(_ num: Int) -> String {
        if num < 0 {
            return "-" + convertToBase7(-num)
        }

        var res = ""
        var num = num

        while num >= 7 {
            res = String(num % 7) + res
            num /= 7
        }
        res = String(num) + res

        return res
    }
}

---

24ms

class Solution {
    func convertToBase7(_ num: Int) -> String {
        guard num != 0 else {
            return "0"
        }
        var num = num
        var flag = true
        if num < 0 {
            flag = false
            num = -num
        }
        var result = ""
        while num > 0 {
            result = "\(num % 7)" + result
            num = num / 7
        }
        return flag ? result : ("-" + result)
    }
}