添加0151.翻转字符串里的单词 Swift版本

problems/0151.翻转字符串里的单词.md

@@ -467,6 +467,85 @@ function reverse(strArr, start, end) {
 }
 ```
 
+Swift:
+
+```swift
+func reverseWords(_ s: String) -> String {
+    var stringArr = removeSpace(s)
+    reverseString(&stringArr, startIndex: 0, endIndex: stringArr.count - 1)
+    reverseWord(&stringArr)
+    return String(stringArr)
+}
+
+/// 1、移除多余的空格（前后所有的空格，中间只留一个空格）
+func removeSpace(_ s: String) -> [Character] {
+    let ch = Array(s)
+    var left = 0
+    var right = ch.count - 1
+    // 忽略字符串前面的所有空格
+    while ch[left] == " " {
+        left += 1
+    }
+    // 忽略字符串后面的所有空格
+    while ch[right] == " " {
+        right -= 1
+    }
+
+    // 接下来就是要处理中间的多余空格
+    var lastArr = Array<Character>()
+    while left <= right {
+        // 准备加到新字符串当中的字符
+        let char = ch[left]
+        // 新的字符串的最后一个字符；或者原字符串中，准备加到新字符串的那个字符；这两个字符当中，只要有一个不是空格，就可以加到新的字符串当中
+        if char != " " || lastArr[lastArr.count - 1] != " "  {
+            lastArr.append(char)
+        }
+      
+        left += 1
+    }
+    return lastArr
+}
+
+/// 2、反转整个字符串
+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
+    }
+}
+
+/// 3、再次将字符串里面的单词反转
+func reverseWord(_ s: inout [Character]) {
+    var start = 0
+    var end = 0
+    var entry = false
+
+    for i in 0..<s.count {
+        if !entry {
+            start = i
+            entry = true
+        }
+      
+        if entry && s[i] == " " && s[i - 1] != " " {
+            end = i - 1
+            entry = false
+            reverseString(&s, startIndex: start, endIndex: end)
+        }
+
+        if entry && (i == s.count - 1) && s[i] != " " {
+            end = i
+            entry = false
+            reverseString(&s, startIndex: start, endIndex: end)
+        }
+    }
+}
+```
+
+
+