Foundations

Core

Foundations are the entry point for the whole repo. This area is for stabilizing contest C++, basic proof habits, and the first patterns that later sections assume.

Use This Area When

• local compile/run/debug still feels noisy
• you can solve some easy problems, but recognition is not stable
• bugs come more from implementation discipline than from missing advanced theory

Start With One Route

If your bottleneck is...	Open first	Then
the very first loop	C++ Language For Contests	Foundations ladders and Weird Algorithm
weak reasoning and debugging discipline	Reasoning And Implementation Discipline	Increasing Array
standard array and search patterns	Sorting	Binary Search, Prefix Sums, Two Pointers

Core Progression

1. Core first
2. C++ workflow, STL, and debugging habits

3. sorting, binary search, prefix sums, difference arrays, two pointers

4. Then add

5. reasoning and implementation discipline
6. bit tricks once one integer starts behaving like packed state

7. recursion and backtracking as the first explicit search-tree bridge

8. Later

9. amortized reasoning
10. recurrence analysis
11. niche language and standard-library tricks

Good First Repo Anchors

• Weird Algorithm
• Missing Number
• Increasing Array
• Factory Machines
• Static Range Sum Queries
• Apartments

Browse All Subtopics

• C++ Language For Contests
• Reasoning And Implementation Discipline
• Bit Tricks
• Recursion And Backtracking
• Sorting
• Binary Search
• Prefix Sums
• Difference Arrays
• Two Pointers

Companion Doors

• Foundations ladders
• Foundations cheatsheet
• Template Library

Go Deeper

• Course: MIT 6.1210 / 6.1220
• Course: Stanford CS161
• Reference: CP-Algorithms
• Practice: CSES Problem Set