fix!: harden sort and BST contracts and enforce CI checks

.githooks/commit-msg

@@ -13,13 +13,14 @@ NC='\033[0m'
 # Valid prefixes (conventional commits)
 valid_prefixes="feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert"
 
-# Pattern: prefix(optional-scope): description
-pattern="^($valid_prefixes)(\(.+\))?: .+"
+# Pattern: prefix(optional-scope)(optional !): description
+pattern="^($valid_prefixes)(\([^)]+\))?!?: .+"
 
 if ! echo "$commit_msg" | head -1 | grep -qE "$pattern"; then
     echo -e "${RED}Invalid commit message format!${NC}"
     echo ""
     echo "Commit message must follow: <type>(<scope>): <description>"
+    echo "Add ! before the colon for a breaking change: <type>(<scope>)!: <description>"
     echo ""
     echo -e "${YELLOW}Valid prefixes:${NC}"
     echo "  feat:     New feature"
@@ -39,6 +40,7 @@ if ! echo "$commit_msg" | head -1 | grep -qE "$pattern"; then
     echo "  fix(rust): resolve memory leak in linked list"
     echo "  docs: update README with examples"
     echo "  test(python): add edge case tests for sorting"
+    echo "  feat(c)!: require path capacity in shortest_path_reconstruct"
     echo ""
     echo -e "Your message: ${RED}$commit_msg${NC}"
     exit 1

.githooks/pre-commit

@@ -25,10 +25,26 @@ if command -v cargo &> /dev/null; then
     fi
 
     echo -n "Running Rust clippy... "
-    if (cd by-language/rust && cargo clippy --all-targets -- -D warnings) &> /dev/null 2>&1; then
+    if (cd by-language/rust && cargo clippy --workspace --all-targets --all-features -- -D warnings) &> /dev/null; then
         echo -e "${GREEN}OK${NC}"
     else
-        echo -e "${RED}WARNINGS${NC} (continuing)"
+        echo -e "${RED}FAILED${NC}"
+        echo "Run 'cd by-language/rust && cargo clippy --workspace --all-targets --all-features -- -D warnings' for details"
+        FAILED=1
+    fi
+fi
+
+# Go checks
+if command -v gofmt &> /dev/null; then
+    echo -n "Checking Go formatting... "
+    unformatted=$(cd by-language/go && gofmt -l .)
+    if [ -z "$unformatted" ]; then
+        echo -e "${GREEN}OK${NC}"
+    else
+        echo -e "${RED}FAILED${NC}"
+        echo "$unformatted"
+        echo "Run 'cd by-language/go && gofmt -w .' to fix"
+        FAILED=1
     fi
 fi
 

.githooks/pre-push

@@ -16,7 +16,7 @@ FAILED=0
 # Rust tests
 if command -v cargo &> /dev/null; then
     echo -e "\n${YELLOW}Running Rust tests...${NC}"
-    if (cd by-language/rust && cargo test --all-features); then
+    if (cd by-language/rust && cargo test --workspace --all-features); then
         echo -e "${GREEN}Rust tests passed!${NC}"
     else
         echo -e "${RED}Rust tests failed!${NC}"
@@ -46,6 +46,39 @@ if command -v make &> /dev/null && [ -f "by-language/c/Makefile" ]; then
     fi
 fi
 
+# Go tests
+if command -v go &> /dev/null; then
+    echo -e "\n${YELLOW}Running Go tests...${NC}"
+    if (cd by-language/go && go vet ./... && go test ./...); then
+        echo -e "${GREEN}Go tests passed!${NC}"
+    else
+        echo -e "${RED}Go tests failed!${NC}"
+        FAILED=1
+    fi
+fi
+
+# TypeScript tests
+if command -v bun &> /dev/null; then
+    echo -e "\n${YELLOW}Running TypeScript tests...${NC}"
+    if (cd by-language/typescript && bun install --frozen-lockfile && bun run typecheck && bun test); then
+        echo -e "${GREEN}TypeScript tests passed!${NC}"
+    else
+        echo -e "${RED}TypeScript tests failed!${NC}"
+        FAILED=1
+    fi
+fi
+
+# Java tests (macOS ships a java stub without a runtime, so probe it)
+if java -version &> /dev/null; then
+    echo -e "\n${YELLOW}Running Java tests...${NC}"
+    if (cd by-language/java && ./gradlew test); then
+        echo -e "${GREEN}Java tests passed!${NC}"
+    else
+        echo -e "${RED}Java tests failed!${NC}"
+        FAILED=1
+    fi
+fi
+
 if [ $FAILED -eq 1 ]; then
     echo -e "\n${RED}Pre-push tests failed. Push aborted.${NC}"
     exit 1

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.10', '3.11', '3.12']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
 
     steps:
       - uses: actions/checkout@v4
@@ -26,6 +26,11 @@ jobs:
           python -m pip install --upgrade pip
           pip install pytest pytest-cov
 
+      - name: Check for invalid escape sequences
+        run: |
+          cd by-language/python
+          python -W error::SyntaxWarning -m compileall -q -f data_structures algorithms tests
+
       - name: Run Python tests
         run: |
           cd by-language/python
@@ -47,6 +52,13 @@ jobs:
           cd by-language/c
           make test
 
+      - name: Run C tests with AddressSanitizer and UBSan
+        run: |
+          cd by-language/c
+          make -B test \
+            CFLAGS='-Wall -Wextra -std=c11 -g -O1 -fsanitize=address,undefined -fno-sanitize-recover=all -fno-omit-frame-pointer -I.' \
+            LDFLAGS='-fsanitize=address,undefined'
+
   rust-tests:
     runs-on: ubuntu-latest
 
@@ -66,18 +78,44 @@ jobs:
       - name: Run clippy
         run: |
           cd by-language/rust
-          cargo clippy --all-targets -- -W clippy::all
+          cargo clippy --workspace --all-targets --all-features -- -D warnings
 
       - name: Run tests
         run: |
           cd by-language/rust
-          cargo test --all-features
+          cargo test --workspace --all-features
+
+      - name: Check no_std build
+        run: |
+          cd by-language/rust
+          cargo check --workspace --no-default-features
+
+      - name: Check documentation
+        env:
+          RUSTDOCFLAGS: -D warnings
+        run: |
+          cd by-language/rust
+          cargo doc --workspace --no-deps
+
+  rust-msrv:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Rust 1.70 (declared rust-version)
+        uses: dtolnay/rust-toolchain@1.70
+
+      - name: Check library crates
+        run: |
+          cd by-language/rust
+          cargo check -p dsa-core -p dsa-data-structures -p dsa-algorithms --lib
 
   go-tests:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: ['1.21', '1.22']
+        go-version: ['1.21', 'stable']
 
     steps:
       - uses: actions/checkout@v4
@@ -87,10 +125,26 @@ jobs:
         with:
           go-version: ${{ matrix.go-version }}
 
+      - name: Check formatting
+        if: matrix.go-version == 'stable'
+        run: |
+          cd by-language/go
+          unformatted=$(gofmt -l .)
+          if [ -n "$unformatted" ]; then
+            echo "Files need gofmt:"
+            echo "$unformatted"
+            exit 1
+          fi
+
+      - name: Run go vet
+        run: |
+          cd by-language/go
+          go vet ./...
+
       - name: Run Go tests
         run: |
           cd by-language/go
-          go test ./...
+          go test -race ./...
 
   typescript-tests:
     runs-on: ubuntu-latest
@@ -104,7 +158,12 @@ jobs:
       - name: Install dependencies
         run: |
           cd by-language/typescript
-          bun install
+          bun install --frozen-lockfile
+
+      - name: Type-check
+        run: |
+          cd by-language/typescript
+          bun run typecheck
 
       - name: Run TypeScript tests
         run: |
@@ -132,4 +191,4 @@ jobs:
       - name: Run Java tests
         run: |
           cd by-language/java
-          gradle test
+          ./gradlew test

README.md

@@ -2,11 +2,14 @@
 
 A comprehensive collection of data structures and algorithms implemented in **C**, **Go**, **Java**, **Python**, **Rust**, and **TypeScript**.
 
-Each implementation includes:
-- Detailed ASCII visual diagrams
-- Time & space complexity analysis
-- LeetCode problem mappings
-- Comprehensive unit tests
+Every language has:
+- Unit tests for each data structure and algorithm
+- Seeded randomized tests that compare implementations against simple reference models
+- Time & space complexity notes
+
+Most C, Python, and Rust sources also include ASCII diagrams and LeetCode problem
+mappings in their header comments. The Go, Java, and TypeScript sources use shorter
+doc comments.
 
 ## Language Requirements
 
@@ -58,8 +61,8 @@ dsa/
 | Stack | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | Queue | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | Deque | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| Circular Queue | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| Min/Max Stack | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
+| Circular Queue | ✓ | ✓ | ✓ | ✓ | - | ✓ |
+| Min/Max Stack | ✓ | ✓ | ✓ | ✓ | - | ✓ |
 | Monotonic Queue | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 
 ### Trees
@@ -89,7 +92,7 @@ dsa/
 | Structure | C | Go | Java | Python | Rust | TypeScript |
 |-----------|:-:|:--:|:----:|:------:|:----:|:----------:|
 | Adjacency List | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| Adjacency Matrix | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
+| Adjacency Matrix | ✓ | ✓ | ✓ | ✓ | - | ✓ |
 | Union-Find | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 
 ### Caches
@@ -122,7 +125,7 @@ dsa/
 | Algorithm | C | Go | Java | Python | Rust | TypeScript |
 |-----------|:-:|:--:|:----:|:------:|:----:|:----------:|
 | Binary Search | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| Two Pointers | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
+| Two Pointers | ✓ | ✓ | ✓ | ✓ | ✓ | - |
 | Sliding Window | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 
 ### Graph
@@ -136,7 +139,8 @@ dsa/
 | Prim's MST | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | Kruskal's MST | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | Topological Sort | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| Tarjan's SCC | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
+| Tarjan's SCC | ✓ | ✓ | ✓ | ✓ | - | ✓ |
+| Kosaraju's SCC | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 
 ### Dynamic Programming
 | Problem | C | Go | Java | Python | Rust | TypeScript |
@@ -155,6 +159,16 @@ dsa/
 | Rabin-Karp | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | Z-Algorithm | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 
+### Go-only modules
+The Go implementation also has algorithm modules that the other languages do not
+have yet:
+
+| Module | Contents |
+|--------|----------|
+| Backtracking | Permutations, subsets, combinations, combination sum, N-Queens, Sudoku, word search, generate parentheses |
+| Greedy | Activity selection, interval problems, fractional knapsack, job sequencing, Huffman encoding, jump game, gas station, task scheduler |
+| Math | GCD/LCM, primality and sieve, prime factors, fast power, Euler's totient, modular inverse, binomial and Catalan numbers, bit tricks |
+
 ## Quick Start
 
 ### C
@@ -192,6 +206,7 @@ cargo test
 ```bash
 cd by-language/typescript
 bun install
+bun run typecheck
 bun test
 ```
 
@@ -205,13 +220,17 @@ APIs should update their arguments before using the revised implementations.
 
 ### Git Hooks (Optional)
 ```bash
-# Install pre-commit and pre-push hooks
+# Install pre-commit, pre-push, and commit-msg hooks
 ./.githooks/install.sh
 ```
 
+The pre-commit hook checks Rust formatting and Clippy, Go formatting, and Python
+lint when `ruff` or `black` is installed. The pre-push hook runs the suite for
+each language whose toolchain is installed.
+
 ## Implementation Template
 
-Each implementation follows a consistent format:
+The C, Python, and Rust header comments follow this format:
 
 ```
 /**