Below is the list for July Leetcode Challenge day wise. With my approach and their code. If approach is little tricky or harder to understand, added comments for the same. Please read and upvote if it is useful for you.

1. Gray Code
2. K Closest Elements
3. Max Sum of Rectangle No Larger Than K
4. Count Vowels Permutation
5. Reshape the Matrix
6. Reduce Array Size to The Half
7. Kth Smallest Element in a Sorted Matrix
8. Maximum Length of Repeated Subarray
9. Longest Increasing Subsequence
10. Decode Ways II
11. Find Median from Data Stream
12. Isomorphic Strings
13. Find Peak Element
14. Custom Sort String
15. Valid Triangle Number
16. 4Sum
17. Three Equal Parts
18. Reverse Nodes in k-Group
19. Lowest Common Ancestor of a Binary Search Tree
20. Shuffle an Array
21. Push Dominoes
22. Partition Array into Disjoint Intervals
23. Binary Tree Pruning
24. Word Ladder II
25. Non-negative Integers without Consecutive Ones
26. Convert Sorted Array to Binary Search Tree
27. 3Sum Closest
28. Beautiful Array
29. 01 Matrix
30. Map Sum Pairs
31. Trapping Rain Water

Thanks for reading. Please upvote if you like.