diff --git a/README.md b/README.md
index 1474203..006ac3a 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
- 
+ 
diff --git a/docs/02-concepts/01-arrays-and-strings.mdx b/docs/02-concepts/01-arrays-and-strings.mdx
index 99c7e30..32c14ff 100644
--- a/docs/02-concepts/01-arrays-and-strings.mdx
+++ b/docs/02-concepts/01-arrays-and-strings.mdx
@@ -63,3 +63,9 @@ Random access in this context means that you can access an element at any index
+
+## Study deck
+
+Drill the essentials — click the deck, then use the arrow keys.
+
+
diff --git a/docs/02-concepts/02-hashing.mdx b/docs/02-concepts/02-hashing.mdx
index 45716b1..0675002 100644
--- a/docs/02-concepts/02-hashing.mdx
+++ b/docs/02-concepts/02-hashing.mdx
@@ -28,3 +28,9 @@ Appending to the end of a list is amortized O(1) time complexity. This means tha
Random access in this context means that you can access an element at any index in constant time.
:::
+
+## Study deck
+
+Drill the essentials — click the deck, then use the arrow keys.
+
+
diff --git a/docs/02-concepts/03-binary-search.mdx b/docs/02-concepts/03-binary-search.mdx
index 7e00cfd..903714a 100644
--- a/docs/02-concepts/03-binary-search.mdx
+++ b/docs/02-concepts/03-binary-search.mdx
@@ -28,3 +28,9 @@ Appending to the end of a list is amortized O(1) time complexity. This means tha
Random access in this context means that you can access an element at any index in constant time.
:::
+
+## Study deck
+
+Drill the essentials — click the deck, then use the arrow keys.
+
+
diff --git a/docs/03-guides/02-two-pointers.mdx b/docs/03-guides/02-two-pointers.mdx
index 5518bcb..8f116fe 100644
--- a/docs/03-guides/02-two-pointers.mdx
+++ b/docs/03-guides/02-two-pointers.mdx
@@ -12,3 +12,9 @@ This page is a scaffold. Notes, canonical problems, and template code are not wr
+
+## Study deck
+
+Drill the essentials — click the deck, then use the arrow keys.
+
+
diff --git a/docs/03-guides/03-prefix-sum.mdx b/docs/03-guides/03-prefix-sum.mdx
index 1bb054f..6083051 100644
--- a/docs/03-guides/03-prefix-sum.mdx
+++ b/docs/03-guides/03-prefix-sum.mdx
@@ -6,3 +6,9 @@ description: 'Precomputed cumulative state for O(1) range queries.'
:::warning[Under construction]
This page is a scaffold. Notes, canonical problems, and template code are not written yet.
:::
+
+## Study deck
+
+Drill the essentials — click the deck, then use the arrow keys.
+
+
diff --git a/docs/03-guides/04-sliding-window.mdx b/docs/03-guides/04-sliding-window.mdx
index 0a9d65c..298759c 100644
--- a/docs/03-guides/04-sliding-window.mdx
+++ b/docs/03-guides/04-sliding-window.mdx
@@ -6,3 +6,9 @@ description: 'Two pointers plus incremental state between them.'
:::warning[Under construction]
This page is a scaffold. Notes, canonical problems, and template code are not written yet.
:::
+
+## Study deck
+
+Drill the essentials — click the deck, then use the arrow keys.
+
+
diff --git a/docs/reference/01-reverse-string.mdx b/docs/reference/01-reverse-string.mdx
new file mode 100644
index 0000000..fe6b466
--- /dev/null
+++ b/docs/reference/01-reverse-string.mdx
@@ -0,0 +1,45 @@
+---
+title: '344. Reverse String'
+description: Write a function that reverses a string. The input string is given as an array of characters s
+sidebar:
+ badge: 'Easy'
+---
+
+Two Pointers
+
+:::warning
+You must do this by modifying the input array in-place with O(1) extra memory.
+:::
+
+### Example 1:
+- Input: `s = ["h","e","l","l","o"]`
+- Output: `["o","l","l","e","h"]`
+
+### Example 2:
+- Input: `s = ["H","a","n","n","a","h"]`
+- Output: `["h","a","n","n","a","H"]`
+
+### Constraints:
+
+- `1 <= s.length <= 10^5`
+- `s[i]` is a printable ascii character.
+
+## Solution
+
+```js
+/**
+ * @param {character[]} s
+ * @return {void} Do not return anything, modify s in-place instead.
+ */
+
+var reverseString = function(s) {
+ let i = 0;
+ let j = s.length - 1;
+
+ while (i < j) {
+ [s[i], s[j]] = [s[j], s[i]];
+ j--;
+ i++;
+ }
+};
+```
diff --git a/docs/reference/02-squares-of-a-sorted-array.mdx b/docs/reference/02-squares-of-a-sorted-array.mdx
new file mode 100644
index 0000000..b8a7dc1
--- /dev/null
+++ b/docs/reference/02-squares-of-a-sorted-array.mdx
@@ -0,0 +1,54 @@
+---
+title: '977. Squares of a Sorted Array'
+description: Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order
+sidebar:
+ badge: 'Easy'
+---
+
+Two Pointers
+
+::::warning
+Squaring each element and sorting the new array is very trivial, could you find an O(n) solution using a different approach?
+::::
+
+### Example 1:
+- Input: `nums = [-4,-1,0,3,10]`
+- Output: `[0,1,9,16,100]`
+- Explanation: After squaring, the array becomes `[16,1,0,9,100]`. After sorting, it becomes `[0,1,9,16,100]`.
+
+### Example 2:
+- Input: `nums = [-7,-3,2,3,11]`
+- Output: `[4,9,9,49,121]`
+
+### Constraints:
+
+- `1 <= nums.length <= 10^4`
+- `-10^4 <= nums[i] <= 10^4`
+- `nums` is sorted in non-decreasing order.
+
+## Solution
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var sortedSquares = function(nums) {
+ let n = nums.length;
+ let ans = new Array(nums.length);
+ let left = 0, right = nums.length - 1;
+
+ for (let i = n -1; i >= 0; i--){
+ let square;
+ if(Math.abs(nums[left]) < Math.abs(nums[right])){
+ square = nums[right];
+ right--;
+ }else{
+ square = nums[left];
+ left++;
+ }
+ ans[i] = square*square;
+ }
+ return ans;
+};
+```
diff --git a/docs/solutions/(two-pointers)/01-reverse-string.mdx b/docs/solutions/(two-pointers)/01-reverse-string.mdx
deleted file mode 100644
index f49c32a..0000000
--- a/docs/solutions/(two-pointers)/01-reverse-string.mdx
+++ /dev/null
@@ -1,10 +0,0 @@
----
-title: '344. Reverse String'
-sidebar:
- badge: 'Easy'
----
-
-Two Pointers
-[Source](https://leetcode.com/problems/reverse-string/)
-
-## Description
diff --git a/docs/solutions/(two-pointers)/02-squares-of-a-sorted-array.mdx b/docs/solutions/(two-pointers)/02-squares-of-a-sorted-array.mdx
deleted file mode 100644
index f893cee..0000000
--- a/docs/solutions/(two-pointers)/02-squares-of-a-sorted-array.mdx
+++ /dev/null
@@ -1,5 +0,0 @@
----
-sidebar:
- icon: code
- badge: '977'
----