Technical coding interviews are a skill. Like any skill, they can be learned with deliberate practice. This guide gives you the exact framework used by engineers who crack interviews at Google, Meta, Amazon, and the fastest-growing startups — without six months of grinding.
The Truth About Coding Interviews
Most people fail coding interviews not because they don't know how to code, but because:
- They can't verbalize their thinking while writing code
- They've memorized solutions instead of understanding patterns
- They panic when stuck and go silent
- They haven't practiced under time pressure
The fix isn't to solve 500 LeetCode problems. It's to understand patterns and build the habit of thinking out loud.
What's Actually Tested
1. Core Data Structures (know these cold)
| Structure | Key operations | When to reach for it | |---|---|---| | Array / Slice | O(1) access, O(n) insert | Random access, two-pointer problems | | Hash Map | O(1) lookup/insert | Counting, deduplication, anagram detection | | Stack | O(1) push/pop | Parentheses matching, monotonic stack problems | | Queue / Deque | O(1) enqueue/dequeue | BFS, sliding window | | Heap (priority queue) | O(log n) push/pop | Top-K, Dijkstra, scheduling | | Binary Tree / BST | O(log n) balanced ops | Hierarchical data, search | | Graph (adjacency list) | Varies | Connectivity, shortest path, topological sort | | Trie | O(m) where m=key length | Prefix search, autocomplete |
2. Algorithm Patterns (learn patterns, not solutions)
- Two pointers: Sorted arrays, palindromes, container with most water
- Sliding window: Max/min subarray of length k, substring problems
- Binary search: Sorted arrays, "find the minimum that satisfies X"
- BFS/DFS: Trees, graphs, grid problems
- Dynamic programming: Overlapping subproblems, optimization
- Backtracking: Permutations, combinations, Sudoku
- Greedy: Interval scheduling, coin change (sometimes)
- Divide and conquer: Merge sort, quicksort, tree problems
3. Complexity Analysis
Every solution needs a time and space complexity explanation. Practice stating it automatically:
- "This is O(n) time because I traverse the array once"