solutions

Author: liuhanqu

README.md

@@ -13,3 +13,10 @@ LeetCode Problems' Solutions in JavaScript
 7.  [从排序数组中删除重复项](./algorithms/easy/removeDuplicates/removeDuplicates.js)
 8.  [反转整数](./algorithms/easy/reverse/reverse.js)
 9.  [第一个错误的版本](./algorithms/easy/solution/solution.js)
+
+## medium
+
+1.  [数组中的第 K 个最大元素](./algorithms/medium/findKthLargest/findKthLargest.js)
+1.  [分类颜色](./algorithms/medium/sortColors/sortColors.js)
+
+## hard

algorithms/medium/findKthLargest/findKthLargest.js

@@ -0,0 +1,12 @@
+// description: https://leetcode-cn.com/explore/interview/card/top-interview-questions-medium/50/sorting-and-searching/98/
+// 数组中的第K个最大元素
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var findKthLargest = function(nums, k) {
+  var snums = nums.sort((a, b) => a - b);
+  return snums[nums.length - k];
+};

algorithms/medium/sortColors/sortColors.js

@@ -0,0 +1,26 @@
+// description: https://leetcode-cn.com/explore/interview/card/top-interview-questions-medium/50/sorting-and-searching/96/
+// 分类颜色
+
+// TODO: 一个仅使用常数空间的一趟扫描算法
+
+/**
+ * @param {number[]} nums
+ * @return {void} Do not return anything, modify nums in-place instead.
+ */
+var sortColors = function(nums) {
+  var counts = [0, 0, 0];
+  var i, count;
+  var j = 0;
+  var len = nums.length;
+
+  for (i = 0; i < len; i++) {
+    counts[nums[i]] = counts[nums[i]] + 1;
+  }
+
+  for (i = 0, len = counts.length; i < len; i++) {
+    count = counts[i];
+    while (count--) {
+      nums[j++] = i;
+    }
+  }
+};