24 → LeetCode Practice

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▶️ pkg5leetcode/ · 249 solutions

Study order

11. Starter 12     pkg5leetcode/leetcode1TwoSum.java · leetcode1222. Blind 75       pkg5leetcode/blind75/33. Official 75    pkg5leetcode/official75/44. Interview 150  pkg5leetcode/interview150/55. Top 100 extras pkg5leetcode/top100/

1java pkg5leetcode/blind75/blind75_LC1TwoSum.java2./run-leetcode-all.ps1    # verify all 249

How to practice each problem

1. Read on LeetCode (use LC number in filename).
2. Solve on paper · state approach + complexity.
3. Code without looking.
4. Run the project solution and compare.
5. Re-implement from memory next day.

Shared helpers (learn once → reuse)

Linked-list and tree problems all need the same node types. Study them once in `pkg5leetcode/common/`:

1javac pkg5leetcode/common/ListNode.java pkg5leetcode/blind75/blind75_LC206ReverseLinkedList.java2java -cp "pkg5leetcode/common;pkg5leetcode/blind75" blind75_LC206ReverseLinkedList

Problem files may still nest a copy of the type so java SomeFile.java works alone — the shape matches common/. Prefer compiling against helpers when practicing for interviews.

14 patterns to master

1. Hashing · 2. Two pointers · 3. Sliding window · 4. Binary search
2. Stack · 6. Linked list · 7. Trees (DFS/BFS) · 8. Graphs
3. Heap · 10. Backtracking · 11. DP · 12. Greedy
4. Intervals · 14. Bit manipulation

Related → LeetCode.md

Related → 17 Print Puzzles

Next → 25 JVM & Memory