Using Python or Java to answer leet code problems to prep for tech interviews
| # | Title | Solution | Time/Space Complexity | Methods/Notes | Date Completed |
|---|---|---|---|---|---|
| 1 | Two Sum | Java | O(N)/O(N) | Hashmap to see if seen the target num subtracted by current number -> return value if have | May 25, 2024 |
| 14 | Longest Common Prefix | Java Python | O(N)/O(M) for both | set empty string, iterate through all the strings at once (need 2 for loops), return when i == len(s) or s[i] != strs[0][i] | Apirl 04, 2024 |
| 21 | Merge Two Sorted Lists | Java | O(N)/O(N) | Creating a new linked list and add in required order | June 5, 2024 |
| 118 | Pascal's Triangle | Java Python | O(N^2)/O(N^2) | Dynamic Programming -> every row is a list/array itself -> recursive calling itself to use previous row to calculate current row | May 25, 2024 |
| 125 | Valid Palindrome | Java | O(N)/O(1) | Two pointers, start at each end and compare | June 1, 2024 |
| 206 | Reverse Linked List | Java | M1: O(N)/O(1) M2: O(N)/O(N) |
M1: Iteratively M2:Recursively | June 5, 2024 |
| 217 | Contains Duplicate | Python | M1: O(N^2)/O(1) M2: O(NlogN)/O(logN) M3: O(N)/O(N) |
M1: Brute Force M2: sort array first, compare adjacent elements M3: put elements into HashMap -> containsKey then return true, else false |
May 25, 2024 |
| 242 | Valid Anagram | Python | M1: O(N)/O(N) M2: O(NlogN)/O(1) but could also be said to be O(N) for space |
M1: using Hashmap to count number of each character M2: sort the string first |
May 26, 2024 |
| 344 | Reverse String | Java | O(N)/O(1) | Two pointers, start at each end and swap characters | June 1, 2024 |
| 671 | Second Minimum Node in a Binary Tree | Java | O(N)/O(N) | DFS -- preorder traversal but custom towards this special kind of tree -> think case by case | Apirl 23, 2024 |
| 746 | Min Cost Climbing Stairs | Java | O(N)/O(1) | DP -> base case first two steps -> loop curr = cost[i] + min(first,second), first = second, second = curr | Apirl 20, 2024 |
| # | Title | Solution | Time/Space Complexity | Methods/Notes | Date Completed |
|---|---|---|---|---|---|
| 11 | Container With Most Water | Java | O(N)/O(1) | two pointers, starting at opposite ends, move smaller pointer after testing area | June 5, 2024 |
| 33 | Search in Rotated Sorted Array | Java | O(logN)/O(1) | binary search | June 5, 2024 |
| 49 | Group Anagrams | Python | O(N)/O(N)) | HashMap of charCount to the words that can make this anagram | May 31, 2024 |
| 143 | Reorder List | Java | O(N)/O(N) | two pointers, one at each end but with linked lists | June 5, 2024 |
| 347 | Top K Frequent Elements | Python | O(N)/O(N)) | Bucket Sort + HashMap and then loop through for highest frequencies | May 31, 2024 |
| 743 | Network Delay Time | Python | O(NLogN)/O(N) O(E*logV) in terms of edges & vertex) |
Dikjstra's Algorithm using MinHeap + stack to visit all nodes and see shortest path/weight | May 20, 2024 |
| 912 | Sort an Array | Java | O(NLogN)/O(logN) | merge sort | May 20, 2024 |
| # | Title | Solution | Time/Space Complexity | Methods/Notes | Date Completed |
|---|---|---|---|---|---|
| 2781 | Length of the Longest Valid Substring | Java | O(N * maxlengthofforbidden^2)/O(sum of forbidden words length) | Sliding Window + brute Force | June 1, 2024 |