docs(docs): add LeetCode problem markdown pages and docs site assets

apps/docs/content/(array)/347-top-k-frequent-elements.mdx

@@ -0,0 +1,51 @@
+---
+title: '347. Top K Frequent Elements'
+description: Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order
+sidebar:
+  label: 'Top K Frequent Elements'
+  badge: 'Medium'
+---
+
+<Badge variant="accent">Hash Table</Badge>
+
+::::warning
+Your algorithm's time complexity must be better than O(n log n), where n is the array's size.
+::::
+
+### Example 1:
+- Input: `nums = [1,1,1,2,2,3], k = 2`
+- Output: `[1,2]`
+
+### Example 2:
+- Input: `nums = [1], k = 1`
+- Output: `[1]`
+
+### Example 3:
+- Input: `nums = [1,2,1,2,1,2,3,1,3,2], k = 2`
+- Output: `[1,2]`
+
+### Constraints:
+
+- `1 <= nums.length <= 10^5`
+- `-10^4 <= nums[i] <= 10^4`
+- `k` is in the range `[1, the number of unique elements in the array]`.
+- It is guaranteed that the answer is unique.
+
+## Solution
+
+```js
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+var topKFrequent = function (nums, k) {
+  const freq = {};
+  for (let n of nums) freq[n] = (freq[n] || 0) + 1;
+
+  return Object.keys(freq)
+    .map(Number)
+    .sort((a, b) => freq[b] - freq[a])
+    .slice(0, k);
+};
+```