[Swift]LeetCode709. 转换成小写字母 | To Lower Case

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Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase. 

Example 1:

Input: "Hello"
Output: "hello"

Example 2:

Input: "here"
Output: "here"

Example 3:

Input: "LOVELY"
Output: "lovely"

---

实现函数 ToLowerCase()，该函数接收一个字符串参数 str，并将该字符串中的大写字母转换成小写字母，之后返回新的字符串。 

示例 1：

输入: "Hello"
输出: "hello"

示例 2：

输入: "here"
输出: "here"

示例 3：

输入: "LOVELY"
输出: "lovely"

---

Runtime: 4 ms

Memory Usage: 19.6 MB

class Solution {
    func toLowerCase(_ str: String) -> String {
        return String(str.unicodeScalars.map { (s) -> Character in
            if s.value >= 65 && s.value <= 90 {
                return Character(UnicodeScalar(s.value + 32)!)
            }
            return Character(UnicodeScalar(s))
        })
    }
}

---

Runtime: 4 ms

Memory Usage: 19.8 MB

class Solution {
    func toLowerCase(_ str: String) -> String {
        var arr:[Character] = Array(str)
        for i in 0..<arr.count
        {
            var char:Character = arr[i]
            if char >= "A" && char <= "Z"
            {
                arr[i] = (char.ascii + 32).ASCII
            }
        }
        return String(arr)
    }
}

//Character扩展 
extension Character  
{  
  //Character转ASCII整数值(定义小写为整数值)
   var ascii: Int {
       get {
           return Int(self.unicodeScalars.first?.value ?? 0)
       }       
    }    
}

//Int扩展
extension Int
{
    //Int转Character,ASCII值(定义大写为字符值)
    var ASCII:Character 
    {
        get {return Character(UnicodeScalar(self)!)}
    }
}

---

4ms

class Solution {
    func ord(ch: String) -> Int? {
    for st in ch.utf16 {
        return Int(st)
    }
    return nil
}

func ord(val: UInt16) -> Character? {
    if let us  = UnicodeScalar(val){
        return Character(us)
    }
    return nil
}
    
    func toLowerCase(_ str: String) -> String {
    guard str.count > 0 else {
        return ""
    }
    var s = Array(str)
    for ch in s.enumerated() {
        if var ordVal = ord(ch: String(ch.element)), ordVal >= 65 && ordVal <= 90 {
            ordVal = ordVal + 32
            if let modVal = ord(val: UInt16(ordVal)) {
                s[ch.offset] = modVal
            }
        }
    }
    return String(s)
    }
}

---

19040kb

class Solution {
    
    func toLowerCase(_ str: String) -> String {
        var word = String()
        for i in str.utf8{
            var i = i
            if i >= 65 && i <= 90 {
                word.append(Character(UnicodeScalar(i + 32)))
            }
            else {
                word.append(Character(UnicodeScalar(i)))
            }
        }
        return word
    }
}

---

19112kb

class Solution {
    func toLowerCase(_ str: String) -> String {
        return String(str.utf8.map({ (ascii) -> Character in
            var charCode = Int(ascii)
            if 65 <= charCode && charCode <= 90 {
                charCode += 32
            }
            return Character(UnicodeScalar(charCode)!)
        }))
    }
}