I write data structures/algorithms as a refresher in my free time.

1. https://leetcode.com/problems/two-sum/
2. https://leetcode.com/problems/3sum/
3. https://leetcode.com/problems/container-with-most-water/
4. https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/
5. https://leetcode.com/problems/merge-sorted-array/
6. https://leetcode.com/problems/move-zeroes/
7. https://leetcode.com/problems/remove-duplicates-from-sorted-array/
8. https://leetcode.com/problems/sort-colors/
9. https://leetcode.com/problems/partition-labels

1. https://leetcode.com/problems/find-all-duplicates-in-an-array
2. https://leetcode.com/problems/product-of-array-except-self/
3. https://leetcode.com/problems/search-a-2d-matrix/

1. https://leetcode.com/problems/valid-palindrome
2. https://leetcode.com/problems/valid-palindrome-ii
3. https://leetcode.com/problems/first-unique-character-in-a-string
4. https://leetcode.com/problems/group-anagrams
5. https://leetcode.com/problems/longest-palindromic-substring

1. https://leetcode.com/problems/most-common-word
2. https://leetcode.com/problems/jump-game (amazing question)
3. https://leetcode.com/problems/jump-game-ii/
4. https://leetcode.com/problems/minimum-size-subarray-sum/

1. https://leetcode.com/problems/linked-list-cycle/
2. https://leetcode.com/problems/reverse-linked-list
3. https://leetcode.com/problems/odd-even-linked-list
4. https://leetcode.com/problems/copy-list-with-random-pointer

1. https://leetcode.com/problems/binary-tree-preorder-traversal/
2. https://leetcode.com/problems/binary-tree-postorder-traversal
3. https://leetcode.com/problems/maximum-depth-of-binary-tree/
4. https://leetcode.com/problems/binary-tree-level-order-traversal/

1. https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal
2. https://leetcode.com/problems/invert-binary-tree
3. https://leetcode.com/problems/binary-tree-right-side-view
4. https://leetcode.com/problems/find-the-celebrity/

1. https://leetcode.com/problems/number-of-islands
2. https://leetcode.com/problems/longest-substring-without-repeating-characters

1. https://leetcode.com/problems/divide-two-integers (Ques that looks easy, is actullay hard but is marked medium)
2. https://leetcode.com/problems/powx-n (same as above.. can't solve these questions without already knowning them)
3. https://leetcode.com/problems/next-permutation
4. https://leetcode.com/problems/verifying-an-alien-dictionary/
5. https://leetcode.com/problems/k-closest-points-to-origin/
6. https://leetcode.com/problems/trapping-rain-wate (very imp question)
7. https://leetcode.com/problems/subarray-sum-equals-k (very tricky)
8. https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses (NICE ;) solution)
9. https://leetcode.com/problems/word-break/
10. https://leetcode.com/problems/add-strings/
11. https://leetcode.com/problems/best-time-to-buy-and-sell-stock
12. https://leetcode.com/problems/combination-sum/

1. https://leetcode.com/problems/lru-cache/submissions/
2. https://leetcode.com/problems/number-of-islands/
3. https://leetcode.com/problems/merge-intervals/
4. https://leetcode.com/problems/maximum-subarray/
5. https://leetcode.com/problems/add-two-numbers/
6. https://leetcode.com/problems/insert-delete-getrandom-o1/
7. https://leetcode.com/problems/kth-largest-element-in-an-array/
8. https://leetcode.com/problems/basic-calculator-ii/
9. https://leetcode.com/problems/word-search/
10. https://leetcode.com/problems/container-with-most-water/
11. https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/
12. https://leetcode.com/problems/letter-combinations-of-a-phone-number/
13. https://leetcode.com/problems/game-of-life/
14. https://leetcode.com/problems/top-k-frequent-elements/
15. https://leetcode.com/problems/rotate-image/
16. https://leetcode.com/problems/spiral-matrix/
17. https://leetcode.com/problems/flatten-nested-list-iterator/
18. https://leetcode.com/problems/powx-n/
19. https://leetcode.com/problems/reverse-integer/
20. https://leetcode.com/problems/longest-consecutive-sequence/
21. https://leetcode.com/problems/search-in-rotated-sorted-array/
22. https://leetcode.com/problems/longest-substring-without-repeating-characters

1. https://leetcode.com/explore/interview/card/google/67/sql-2/3044/
2. https://leetcode.com/explore/interview/card/google/67/sql-2/3046

1. https://leetcode.com/problems/next-permutation/
2. https://leetcode.com/problems/multiply-strings/
3. https://leetcode.com/problems/jump-game
4. https://leetcode.com/problems/plus-one/
5. https://leetcode.com/problems/missing-ranges
6. https://leetcode.com/problems/next-closest-time/
7. https://leetcode.com/problems/expressive-words/
8. https://leetcode.com/problems/find-and-replace-in-string/
9. https://leetcode.com/problems/maximize-distance-to-closest-person/
10. https://leetcode.com/problems/minimum-cost-to-hire-k-workers
11. https://leetcode.com/problems/valid-parentheses/

1. https://leetcode.com/problems/remove-nth-node-from-end-of-list/
2. https://leetcode.com/problems/merge-two-sorted-lists/
3. https://leetcode.com/problems/copy-list-with-random-pointer/

1. https://leetcode.com/problems/binary-tree-maximum-path-sum/
2. https://leetcode.com/problems/course-schedule
3. https://leetcode.com/problems/count-complete-tree-nodes/
4. https://leetcode.com/problems/longest-increasing-path-in-a-matrix
5. https://leetcode.com/problems/decode-string
6. https://leetcode.com/problems/evaluate-division/
7. https://leetcode.com/problems/diameter-of-binary-tree
8. https://leetcode.com/problems/cracking-the-safe

1. https://leetcode.com/problems/word-squares/
2. https://leetcode.com/problems/strobogrammatic-number-ii/
3. https://leetcode.com/problems/word-search-ii/
4. https://leetcode.com/problems/letter-combinations-of-a-phone-number/ (same as topinterview)
5. https://leetcode.com/problems/generate-parentheses/
6. https://leetcode.com/problems/android-unlock-patterns/

Some solutions are inspired/copied from discussions/solutions section of leetcode.