docs: 【0055右旋字符串】JavaScript部分实现

Author: songlongfei1

problems/kamacoder/0055.右旋字符串.md

@@ -254,7 +254,37 @@ func main(){
 
 
 ### JavaScript：
+```javascript
+// JS中字符串内不可单独修改
+
+// 右旋转
+function reverseLeftWords(s, k) {
+  const reverse = (sList, start, end) => {
+    for (let i = start, j = end; i < j; i++, j--) {
+      [sList[i], sList[j]] = [sList[j], sList[i]];
+    }
+  }
+  const sList = Array.from(s);
+  reverse(sList, 0, sList.length - k - 1);
+  reverse(sList, sList.length - k, sList.length - 1);
+  reverse(sList, 0, sList.length - 1);
+  return sList.join('');
+}
 
+// 左旋转
+var reverseLeftWords = function(s, n) {
+  const reverse = (sList, start, end) => {
+    for (let i = start, j = end; i < j; i++, j--) {
+      [sList[i], sList[j]] = [sList[j], sList[i]];
+    }
+  }
+  const sList = s.split('');
+  reverse(sList, 0, n - 1);
+  reverse(sList, n, sList.length - 1);
+  reverse(sList, 0, sList.length - 1);
+  return sList.join('');
+};
+```
 
 ### TypeScript：