Update README.md

Author: soapyigu

README.md

@@ -19,6 +19,7 @@
 * [Google](#google)
 * [Facebook](#facebook)
 * [LinkedIn](#linkedin)
+* [Amazon](#amazon)
 * [Microsoft](#microsoft)
 
 ## Array
@@ -228,6 +229,22 @@
 [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/)| [Swift](./DP/MaximumProductSubarray.swift)| Medium| ★★★|
 [Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/)| [Swift](./Array/ProductExceptSelf.swift)| Medium| ★★★|
 
+## Amazon
+| Title | Solution | Difficulty | Frequency |
+| ----- | -------- | ---------- | --------- |
+[Two Sum](https://leetcode.com/problems/two-sum/)| [Swift](./Array/TwoSum.swift)| Easy| ★★★★★★|
+[Number of Islands](https://leetcode.com/problems/number-of-islands/)| [Swift](./DFS/NumberofIslands.swift)| Medium| ★★|
+[Add Two Numbers](https://leetcode.com/problems/add-two-numbers/)| [Swift](./Math/AddTwoNumbers.swift)| Medium| ★★|
+[Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)| [Swift](./LinkedList/ReverseLinkedList.swift)| Easy| ★★|
+[Valid Parentheses](https://leetcode.com/problems/valid-parentheses/)| [Swift](./Stack/ValidParentheses.swift)| Easy| ★★|
+[Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/)| [Swift](./String/LongestSubstringWithoutRepeatingCharacters.swift)| Medium| ★★|
+[Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)| [Swift](./DFS/LetterCombinationsPhoneNumber.swift)| Medium| ★★|
+[Valid Anagram](https://leetcode.com/problems/valid-anagram/)| [Swift](./String/ValidAnagram.swift)| Easy| ★★|
+[Rotate Image](https://leetcode.com/problems/rotate-image/)| [Swift](./Array/RotateImage.swift)| Medium| ★★|
+[Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/)| [Swift](./DP/BestTimeBuySellStock.swift)| Easy| ★★|
+[3Sum](https://leetcode.com/problems/3sum/)| [Swift](./Array/ThreeSum.swift)| Medium| ★★|
+[Sliding Window Maximum ](https://leetcode.com/problems/sliding-window-maximum/)| [Swift](./Array/SlidingWindowMaximum.swift)| Hard| ★★|
+
 ## Microsoft
 | Title | Solution | Difficulty | Frequency |
 | ----- | -------- | ---------- | --------- |