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Practice

A worked bank of data-structures & algorithms problems in Java. Every one: statement → approach → solution → complexity → follow-ups. Grouped by pattern, because the pattern is the transferable skill.

75 problems · 9 patterns · 24 templates

Arrays & Strings

15
most common · master first

Linked Lists

10
pointers · dummy nodes · O(1) space

Trees & BST

10
highest frequency · DFS/BFS recursion

Graphs

8
BFS · DFS · Union-Find · Dijkstra

Dynamic Programming

10
most feared · pattern recognition wins

Heaps & Priority Queue

6
top-K · merge-K · streaming

Backtracking

5
choose → explore → un-choose

Binary Search

5
sorted data · search on answer

Bit Manipulation

6
XOR tricks · Kernighan · masks
Muscle-Memory Templates8 pattern skeletons you write without thinking · 24 templates→Lead Engineer Focus — E5metaThe current senior-IC loop + 58 high-frequency coding questions in Java→