update readme

Author: hogan-tech

.github/Question List.txt

@@ -12,4 +12,5 @@
 0234-palindrome-linked-list python easy
 1119-remove-vowels-from-a-string python easy
 0143-reorder-list python medium
-0021-merge-two-sorted-lists javascript easy
+0021-merge-two-sorted-lists javascript easy
+0442-find-all-duplicates-in-an-array python medium

README.md

@@ -201,6 +201,7 @@ The solutions are organized as follows:
 | 0416 | [Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum/)                                                                             | [Python](./0416-partition-equal-subset-sum/0416-partition-equal-subset-sum.py)                                                                                                                                                                                                 | [Medium](./0416-partition-equal-subset-sum/README.md)                                     |
 | 0438 | [Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/)                                                                       | [Python](./0438-find-all-anagrams-in-a-string/0438-find-all-anagrams-in-a-string.py)                                                                                                                                                                                           | [Medium](./0438-find-all-anagrams-in-a-string/README.md)                                  |
 | 0439 | [Ternary Expression Parser](https://leetcode.com/problems/ternary-expression-parser/)                                                                               | [Python](./0439-ternary-expression-parser/0439-ternary-expression-parser.py)                                                                                                                                                                                                   | [Medium](./0439-ternary-expression-parser/README.md)                                      |
+| 0442 | [Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array/)                                                                   | [Python](./0442-find-all-duplicates-in-an-array/0442-find-all-duplicates-in-an-array.py)                                                                                                                                                                                       | [Medium](./0442-find-all-duplicates-in-an-array/README.md)                                |
 | 0446 | [Arithmetic Slices II - Subsequence](https://leetcode.com/problems/arithmetic-slices-ii-subsequence/)                                                               | [Python](./0446-arithmetic-slices-ii-subsequence/0446-arithmetic-slices-ii-subsequence.py)                                                                                                                                                                                     | [Hard](./0446-arithmetic-slices-ii-subsequence/README.md)                                 |
 | 0451 | [Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency/)                                                                         | [Python](./0451-sort-characters-by-frequency/0451-sort-characters-by-frequency.py)                                                                                                                                                                                             | [Medium](./0451-sort-characters-by-frequency/README.md)                                   |
 | 0452 | [Minimum Number of Arrows to Burst Balloons](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/)                                             | [Python](./0452-minimum-number-of-arrows-to-burst-balloons/0452-minimum-number-of-arrows-to-burst-balloons.py)                                                                                                                                                                 | [Medium](./0452-minimum-number-of-arrows-to-burst-balloons/README.md)                     |