diff --git a/problems/剑指Offer58-II.左旋转字符串.md b/problems/剑指Offer58-II.左旋转字符串.md index f4d3368c..d8aaca67 100644 --- a/problems/剑指Offer58-II.左旋转字符串.md +++ b/problems/剑指Offer58-II.左旋转字符串.md @@ -214,6 +214,34 @@ var reverseLeftWords = function (s, n) { }; ``` +Swift: + +```swift +func reverseLeftWords(_ s: String, _ n: Int) -> String { + var ch = Array(s) + let len = ch.count + // 反转区间[0, n - 1] + reverseString(&ch, startIndex: 0, endIndex: n - 1) + // 反转区间[n, len - 1] + reverseString(&ch, startIndex: n, endIndex: len - 1) + // 反转区间[0, len - 1],也就是整个字符串反转 + reverseString(&ch, startIndex: 0, endIndex: len - 1) + return String(ch) +} + +func reverseString(_ s: inout [Character], startIndex: Int, endIndex: Int) { + var start = startIndex + var end = endIndex + while start < end { + (s[start], s[end]) = (s[end], s[start]) + start += 1 + end -= 1 + } +} +``` + + +