docs(docs): add Approach diagrams and Explanation sections to LeetCode problem documentation

apps/docs/content/(array)/973-k-closest-points-to-origin.mdx

@@ -23,6 +23,23 @@ sidebar:
 - `1 <= k <= points.length <= 10^4`
 - `-10^4 <= xi, yi <= 10^4`
 
+## Approach
+
+```mermaid
+flowchart TD
+  S(["kClosest(points, k)"]) --> I["minHeap = []"]
+  I --> F{"more x, y in points?"}
+  F -- yes --> D["dist = x**2 + y**2 — squared distance orders the same as sqrt"]
+  D --> A["minHeap.append([dist, x, y])"]
+  A --> F
+  F -- no --> H["heapq.heapify(minHeap), res = [] — O(n) build, smallest dist on top"]
+  H --> W{"k > 0?"}
+  W -- yes --> P["dist, x, y = heapq.heappop(minHeap)"]
+  P --> R["res.append([x, y]), k -= 1"]
+  R --> W
+  W -- no --> E(["return res"])
+```
+
 ## Solution
 
 ```py
@@ -46,3 +63,7 @@ class Solution:
 
         return res
 ```
+
+## Explanation
+
+<YouTube id="rI2EBUEMfTk" title="K Closest Points to Origin - Heap / Priority Queue - Leetcode 973 - Python" />