[Swift]LeetCode344. 反转字符串 | Reverse String

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Write a function that takes a string as input and returns the string reversed.

Example 1:

Input: "hello"
Output: "olleh"

Example 2:

Input: "A man, a plan, a canal: Panama"
Output: "amanaP :lanac a ,nalp a ,nam A"

---

编写一个函数，其作用是将输入的字符串反转过来。

示例 1:

输入: "hello"
输出: "olleh"

示例 2:

输入: "A man, a plan, a canal: Panama"
输出: "amanaP :lanac a ,nalp a ,nam A"

---

20ms

class Solution {
    func reverseString(_ s: String) -> String {
        guard s.count > 1 else {
            return s
        }

        var chars = s.utf8CString
        var low = 0
        var high = chars.count - 2
        while low < high {
            chars.swapAt(low, high)
            low += 1
            high -= 1
        }
        return String(cString: Array(chars))
    }
}

---

24ms

class Solution {
    func reverseString(_ s: String) -> String {
        var index = s.endIndex
        var result = ""

        while index != s.startIndex {
            index = s.index(before: index)
            result.append(s[index])
        }
        
        return result
    }
}

---

28ms

class Solution {
    func reverseString(_ s: String) -> String{
        var startIndex = 0
        var endIndex = s.count-1
        var array = s.cString(using:.utf8)!
        while startIndex<endIndex {
            let char = array[startIndex]
            array[startIndex] = array[endIndex]
            array[endIndex] = char
            startIndex+=1
            endIndex-=1
        }
        return String.init(utf8String: array)!
    }
}

---

36ms

class Solution {
    func reverseString(_ s: String) -> String {
        var chars = s.cString(using: String.Encoding.utf8)!
        var left = 0
        var right = s.count - 1
        
        while left < right {
            
            let char = chars[left]
            chars[left] = chars[right]
            chars[right] = char
            
            left = left + 1
            right = right - 1
        }
        
        return String.init(utf8String: chars)!
    }
}