Add CLAUDE.md with build commands and architecture guide (williamfiset#1249)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: williamfiset

CLAUDE.md

@@ -0,0 +1,79 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build System
+
+This project uses **Bazel** as its build system (requires JDK 8+). Dependencies are managed via Maven through `rules_jvm_external` and declared in `MODULE.bazel`.
+
+## Commands
+
+**Run all tests:**
+```bash
+bazel test //src/test/...
+```
+
+**Run tests for a specific package:**
+```bash
+bazel test //src/test/java/com/williamfiset/algorithms/graphtheory:all
+bazel test //src/test/java/com/williamfiset/algorithms/sorting:all
+```
+
+**Run a single test class:**
+```bash
+bazel test //src/test/java/com/williamfiset/algorithms/graphtheory:BoruvkasTest
+```
+
+**Run a specific algorithm (with `main` method):**
+```bash
+bazel run //src/main/java/com/williamfiset/algorithms/graphtheory:BinarySearch
+bazel run //src/main/java/com/williamfiset/algorithms/search:BinarySearch
+```
+
+**Alternative (without Bazel):**
+```bash
+mkdir classes
+javac -sourcepath src/main/java -d classes src/main/java/com/williamfiset/algorithms/search/BinarySearch.java
+java -cp classes com.williamfiset.algorithms.search.BinarySearch
+```
+
+## Project Structure
+
+```
+src/
+  main/java/com/williamfiset/algorithms/
+    datastructures/   # Data structure implementations
+    dp/               # Dynamic programming algorithms + examples/
+    geometry/         # Computational geometry
+    graphtheory/      # Graph algorithms
+      networkflow/    # Max flow, min cost flow, bipartite matching
+      treealgorithms/ # Tree-specific algorithms (LCA, rooting, isomorphism)
+    linearalgebra/    # Matrix operations
+    math/             # Number theory, primes, FFT
+    other/            # Miscellaneous (bit manipulation, permutations, etc.)
+    search/           # Search algorithms
+    sorting/          # Sorting algorithms
+    strings/          # String algorithms
+    utils/            # Shared utilities
+      graphutils/     # Graph construction helpers
+
+  test/java/com/williamfiset/algorithms/
+    <mirrors main structure>
+```
+
+## Architecture Patterns
+
+**BUILD files:** Every package has a Bazel `BUILD` file. The main source `BUILD` files define a `java_library` target (named after the package, e.g., `graphtheory`) plus individual `java_binary` targets per class. Test `BUILD` files define `java_test` targets per test class using JUnit 5 via `ConsoleLauncher`.
+
+**Test framework:** Tests use JUnit 5 (Jupiter) with some legacy JUnit 4. New tests should use JUnit 5.
+
+**Graph representation:** Most graph algorithms accept adjacency lists built with `List<List<Edge>>` or similar structures. Many solvers are implemented as classes where you construct the solver, add edges, then call a `solve()` method.
+
+**Network flow base:** Flow algorithms in `networkflow/` share a common abstract solver pattern — `NetworkFlowSolverBase` is extended by concrete implementations (Dinic's, Ford-Fulkerson, etc.).
+
+**When adding a new algorithm:**
+1. Add the `.java` file in the appropriate `src/main/java/...` package
+2. Add a `java_binary` entry in that package's `BUILD` file
+3. Add a test file in the corresponding `src/test/java/...` package
+4. Add a `java_test` entry in the test `BUILD` file
+5. Update `README.md` with the new algorithm entry