Merge branch 'master' into graphics/spirograph

.clang-tidy

@@ -0,0 +1,6 @@
+---
+Checks:          '-*,google-*,cppcoreguidelines-*,-cppcoreguidelines-avoid-magic-numbers,-cppcoreguidelines-pro-bounds-*,openmp-*,performance-*,portability-*,modernize-*,-modernize-use-trailing-*'
+WarningsAsErrors: ''
+HeaderFilterRegex: ''
+AnalyzeTemporaryDtors: false
+FormatStyle:     '{ BasedOnStyle: Google, UseTab: Never, IndentWidth: 4, TabWidth: 4, AllowShortIfStatementsOnASingleLine: false, IndentCaseLabels: true, ColumnLimit: 80, AccessModifierOffset: -3, AlignConsecutiveMacros: true }'

.github/workflows/awesome_workflow.yml

@@ -16,7 +16,9 @@ jobs:
       - name: requirements
         run: | 
           sudo apt -qq -y update
-          sudo apt -qq install clang-format
+          sudo apt -qq install clang-tidy-10
+        # checks are passing with less errors when used with this version. 
+        # The default installs v6.0 which did not work out well in my tests
       - name: Setup Git Specs
         run: |
           git config --global user.name github-actions
@@ -43,18 +45,6 @@ jobs:
             fi
           done
           git commit -am "formatting filenames $GITHUB_SHA" ||  true
-      - name: Clang Formatter
-        run: |
-          for fname in $(find . -name '*.cpp' -o -name '*.h')
-          do 
-            clang-format --verbose -i --style="$line1 $line2 $line3 $line4" "$fname"
-          done
-          git commit -am "formatting source-code for $GITHUB_SHA" ||  true
-        env:
-          line1: "{ BasedOnStyle: Google, UseTab: Never,"
-          line2: "IndentWidth: 4, TabWidth: 4, "
-          line3: "AllowShortIfStatementsOnASingleLine: false, IndentCaseLabels: false,"
-          line4: "ColumnLimit: 80, AccessModifierOffset: -3 }"
 
       - name: Update DIRECTORY.md
         shell: python
@@ -100,24 +90,21 @@ jobs:
 
             with open("DIRECTORY.md", "w") as out_file:
                 out_file.write(build_directory_md(".") + "\n")
-      - name: Update DIRECTORY.md
+      - name: Commit DIRECTORY.md
+        run: git commit -m "updating DIRECTORY.md" DIRECTORY.md ||  true
+      - name: Get file changes
         run: |
-          cat DIRECTORY.md
-          git config --global user.name github-actions
-          git config --global user.email '${GITHUB_ACTOR}@users.noreply.github.com'
-          git remote set-url origin https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/$GITHUB_REPOSITORY
-          git add DIRECTORY.md
-          git commit -am "updating DIRECTORY.md" ||  true
-          git push --force origin HEAD:$GITHUB_REF || true
-      - name: Install CPPLINT
-        run: |
-          python -m pip install cpplint
           git remote -v
           git branch
           git remote set-url origin https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/$GITHUB_REPOSITORY
           git diff --diff-filter=dr --name-only origin/master > git_diff.txt
           echo "Files changed-- `cat git_diff.txt`"
-      - name: cpplint_modified_files
+      - name: Configure for static lint checks
+        # compiling first gives clang-tidy access to all the header files and settings used to compile the programs. 
+        # This will check for macros, if any, on linux and not for Windows. But the use of portability checks should 
+        # be able to catch any errors for other platforms.
+        run: cmake -B build -S . -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+      - name: Lint modified files
         shell: python
         run: |
           import os
@@ -135,9 +122,9 @@ jobs:
           if not cpp_files:
             sys.exit(0)
 
-          print("cpplint:")
           for cpp_file in cpp_files:
-            subprocess.run(["cpplint", "--filter=-legal/copyright,-build/include", cpp_file], check=True, text=True)
+            subprocess.run(["clang-tidy-10", "--fix", "-p=build", cpp_file, "--"], 
+              check=True, text=True, stderr=subprocess.STDOUT)
 
           # print("g++:")
           # compile_exts = tuple(".c .c++ .cc .cpp .cu .cxx".split())
@@ -163,6 +150,11 @@ jobs:
           bad_files = len(upper_files + space_files + nodir_files)
           if bad_files:
             sys.exit(bad_files)
+      - name: Commit and push changes
+        run: |
+          git diff DIRECTORY.md
+          git commit -am "clang-tidy fixes for $GITHUB_SHA" ||  true
+          git push --force origin HEAD:$GITHUB_REF || true
 
   build:
     name: Compile checks

.gitpod.yml

@@ -7,6 +7,7 @@ github:
     addComment: false
     addCheck: false
     master: true
+    branches: true
     pullRequestsFromForks: true
 
 vscode:

CONTRIBUTING.md

@@ -28,8 +28,85 @@ We are very happy that you consider implementing algorithms and data structures
 - Strictly use snake_case (underscore_separated) in filenames.
 - If you have added or modified code, please make sure the code compiles before submitting.
 - Our automated testing runs [__cpplint__](https://github.com/cpplint/cpplint) on all pull requests so please be sure that your code passes before submitting.
+- Please conform to [doxygen](https://www.doxygen.nl/manual/docblocks.html) standard and document the code as much as possible. This not only facilitates the readers but also generates the correct info on website.
 - **Be consistent in use of these guidelines.**
 
+#### Documentation
+- Make sure you put useful comments in your code.  Do not comment things that are obvious.
+- Please avoid creating new directories if at all possible. Try to fit your work into the existing directory structure. If you want to create a new directory, then please check if a similar category has been recently suggested or created by other pull requests.
+- If you have modified/added documentation, please ensure that your language is concise and contains no grammar errors.
+- Do not update README.md along with other changes, first create an issue and then link to that issue in your pull request to suggest specific changes required to README.md
+- The repository follows [Doxygen](https://www.doxygen.nl/manual/docblocks.html) standards and auto-generates the [repo website](https://thealgorithms.github.io/C-Plus-Plus). Please ensure the code is documented in this structure. Sample implementation is given below.
+
+#### Test
+- Make sure to add examples and test cases in your main() function.
+- If you find any algorithm or document without tests, please feel free to create a pull request or issue describing suggested changes.
+- Please try to add one or more `test()` functions that will invoke the algorithm implementation on random test data with expected output. Use `assert()` function to confirm that the tests will pass.
+
+#### Typical structure of a program:
+```cpp
+/**
+ * @file 
+ * @brief Add one line description here
+ * @details 
+ * This is a multi line
+ * description containing links, references,
+ * math equations, etc
+ * @author [Name](https://github.com/handle)
+ * @see related_file.cpp, another_file.cpp
+ */
+
+#include 
+
+/** 
+ * @namespace <check from other files in this repo>
+ */
+namespace name {
+
+/**
+ * Class documentation
+ */
+class cls_name{
+ private:
+    int var1;  ///< short info of this variable
+    char *msg;  ///< short info
+ 
+ public:
+ // other members also documented as below
+}
+
+/**
+ * Function documentation 
+ * @tparam T this is a one-line info about T
+ * @param param1 on-line info about param1
+ * @param param2 on-line info about param2
+ * @returns `true` if ...
+ * @returns `false` if ... 
+ */
+template<class T>
+bool func(int param1, T param2) {
+    // function statements here 
+    if(/*something bad*/)
+        return false;
+
+    return true;
+}
+
+/** Test function */
+void test() {
+ /* some statements */
+ assert(func(...) == ...); // this ensures that the algorithm works as expected 
+
+ // can have multiple checks
+}
+
+/** Main function */
+int main(int argc, char *argv[]) {
+    // code here
+    return 0;
+}
+```
+
 #### New File Name guidelines
 - Use lowercase words with ``"_"`` as separator
 - For instance 
@@ -70,16 +147,6 @@ Common prefixes:
 - docs: Documentation changes
 - test: Correct existing tests or add new ones
 
-#### Documentation
-- Make sure you put useful comments in your code.  Do not comment things that are obvious.
-- Please avoid creating new directories if at all possible. Try to fit your work into the existing directory structure. If you want to create a new directory, then please check if a similar category has been recently suggested or created by other pull requests.
-- If you have modified/added documentation, please ensure that your language is concise and contains no grammar errors.
-- Do not update README.md along with other changes, first create an issue and then link to that issue in your pull request to suggest specific changes required to README.md
-
-#### Test
-- Make sure to add examples and test cases in your main() function.
-- If you find any algorithm or document without tests, please feel free to create a pull request or issue describing suggested changes.
-
 ### Pull Requests
 - Checkout our [pull request template](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/.github/pull_request_template.md)
 

math/sieve_of_eratosthenes.cpp

@@ -10,25 +10,21 @@
  * @see primes_up_to_billion.cpp prime_numbers.cpp
  */
 
-#include <iostream>
-
-/** Maximum number of primes */
-#define MAX 10000000
-
-/** array to store the primes */
-bool isprime[MAX];
+#include <iostream> // for io operations
 
 /**
  * This is the function that finds the primes and eliminates
  * the multiples.
+ * @param N number of primes to check
+ * @param [out] isprime a boolean array of size `N` identifying if `i`^th number is prime or not
  */
-void sieve(uint32_t N) {
-    isprime[0] = false;
-    isprime[1] = false;
-    for (uint32_t i = 2; i <= N; i++) {
-        if (isprime[i]) {
-            for (uint32_t j = (i << 1); j <= N; j += i) {
-                isprime[j] = false;
+void sieve(uint32_t N, bool *isprime) {
+    isprime[0] = true;
+    isprime[1] = true;
+    for (uint32_t i = 2; i * i <= N; i++) {
+        if (!isprime[i]) {
+            for (uint32_t j = (i << 1); j <= N; j = j + i) {
+                isprime[j] = true;
             }
         }
     }
@@ -36,10 +32,12 @@ void sieve(uint32_t N) {
 
 /**
  * This function prints out the primes to STDOUT
+ * @param N number of primes to check
+ * @param [in] isprime a boolean array of size `N` identifying if `i`^th number is prime or not
  */
-void print(uint32_t N) {
-    for (uint32_t i = 1; i <= N; i++) {
-        if (isprime[i]) {
+void print(uint32_t N, const bool *isprime) {
+    for (uint32_t i = 2; i <= N; i++) {
+        if (!isprime[i]) {
             std::cout << i << ' ';
         }
     }
@@ -47,19 +45,14 @@ void print(uint32_t N) {
 }
 
 /**
- * Initialize the array
+ * Main function
  */
-void init() {
-    for (uint32_t i = 1; i < MAX; i++) {
-        isprime[i] = true;
-    }
-}
-
-/** main function */
 int main() {
     uint32_t N = 100;
-    init();
-    sieve(N);
-    print(N);
+    bool *isprime = new bool[N];
+    sieve(N, isprime);
+    print(N, isprime);
+    delete[] isprime;
+
     return 0;
 }