Rotate Array

Author: w2xi

README.md

@@ -6,4 +6,5 @@
 |2|[两数相加](https://leetcode-cn.com/problems/add-two-numbers/)|[JavaScript](./algorithms/add-two-numbers.js)|Medium|
 |7|[整数反转](https://leetcode-cn.com/problems/reverse-integer/)|[JavaScript](./algorithms/reverse-integer.js)|Medium|
 |9|[回文数](https://leetcode-cn.com/problems/palindrome-number/)|[JavaScript](./algorithms/palindrome-number.js)|Easy|
-|14|[最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)|[JavaScript](./algorithms/longest-common-prefix.js)|Easy|
+|14|[最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)|[JavaScript](./algorithms/longest-common-prefix.js)|Easy|
+|189|[轮转数组](https://leetcode-cn.com/problems/rotate-array/)|[JavaScript](./algorithms/rotate-array.js)|Medium|

algorithms/rotate-array.js

@@ -0,0 +1,39 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {void} Do not return anything, modify nums in-place instead.
+ */
+
+// 空间复杂度O(1)
+var rotate = function (nums, k) {
+  k %= nums.length;
+
+  const reverse = (nums, start, end) => {
+    while (start < end) {
+      [nums[start++], nums[end--]] = [nums[end], nums[start]];
+    }
+  };
+
+  // 反转整个数组
+  reverse(nums, 0, nums.length - 1);
+  // 反转前k个元素
+  reverse(nums, 0, k - 1);
+  // 反转后k后面的元素
+  reverse(nums, k, nums.length - 1);
+};
+
+// 空间复杂度O(n)
+var rotate = function (nums, k) {
+  const len = nums.length;
+  const copy = [];
+
+  for (let i = 0; i < len; i++) {
+    copy.push(nums[i]);
+  }
+
+  for (let i = 0; i < len; i++) {
+    const nextIndex = (i + k) % len;
+
+    nums[nextIndex] = copy[i];
+  }
+};