fix: Array right rotation (#1793)

* Create reverse_binary_tree.cpp

* Added documentation

Added Documentation for the level_order_traversal() function, and implemented a print() function to display the tree to STDOUT

* Added documentation

* Renamed tests to test

* Fixed issue with incorrect using statement

* updating DIRECTORY.md

* clang-format and clang-tidy fixes for fb86292

* Added Test cases

* Update operations_on_datastructures/reverse_binary_tree.cpp

Co-authored-by: David Leal <[email protected]>

* Update operations_on_datastructures/reverse_binary_tree.cpp

Co-authored-by: David Leal <[email protected]>

* Update operations_on_datastructures/reverse_binary_tree.cpp

Co-authored-by: David Leal <[email protected]>

* Update operations_on_datastructures/reverse_binary_tree.cpp

Co-authored-by: David Leal <[email protected]>

* Update operations_on_datastructures/reverse_binary_tree.cpp

Co-authored-by: David Leal <[email protected]>

* Changed int to int64_t

* Updated documentation wording

* Rewrote array_right_rotation by modifying code from array_left_rotation

* Minor documentation changes

* clang-format and clang-tidy fixes for 16672f0

* Update operations_on_datastructures/array_right_rotation.cpp

Co-authored-by: David Leal <[email protected]>

* Changed int to size_t

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: David Leal <[email protected]>

Author: 3 people

operations_on_datastructures/array_right_rotation.cpp

@@ -1,27 +1,175 @@
-#include <iostream>
-using namespace std;
-int main() {
-    int n, k;
-    cout << "Enter size of array=\t";
-    cin >> n;
-    cout << "Enter Number of indices u want to rotate the array to right=\t";
-    cin >> k;
-    int a[n];
-    cout << "Enter elements of array=\t";
-    for (int i = 0; i < n; i++) cin >> a[i];
-    int temp = 0;
-    for (int i = 0; i < k; i++) {
-        temp = a[n - 1];
-        for (int j = n - 1; j >= 0; j--) {
-            if (j == 0) {
-                a[j] = temp;
-            } else {
-                a[j] = a[j - 1];
-            }
-        }
+/**
+ * @file
+ * @brief Implementation for the [Array right
+ * Rotation](https://www.javatpoint.com/program-to-right-rotate-the-elements-of-an-array)
+ * algorithm.
+ * @details Shifting an array to the right involves moving each element of the
+ * array so that it occupies a position of a certain shift value after its
+ * current one. This implementation uses a result vector and does not mutate the
+ * input.
+ * @see array_left_rotation.cpp
+ * @author [Alvin](https://github.com/polarvoid)
+ */
+
+#include <cassert>   /// for assert
+#include <iostream>  /// for IO operations
+#include <vector>    /// for std::vector
+
+/**
+ * @namespace operations_on_datastructures
+ * @brief Operations on Data Structures
+ */
+namespace operations_on_datastructures {
+
+/**
+ * @brief Prints the values of a vector sequentially, ending with a newline
+ * character.
+ * @param array Reference to the array to be printed
+ * @returns void
+ */
+void print(const std::vector<int32_t> &array) {
+    for (int32_t i : array) {
+        std::cout << i << " ";  /// Print each value in the array
+    }
+    std::cout << "\n";  /// Print newline
+}
+
+/**
+ * @brief Shifts the given vector to the right by the shift amount and returns a
+ * new vector with the result. The original vector is not mutated.
+ * @details Shifts the values of the vector, by creating a new vector and adding
+ * values from the shift index to the end, then appending the rest of the
+ * elements to the start of the vector.
+ * @param array A reference to the input std::vector
+ * @param shift The amount to be shifted to the right
+ * @returns A std::vector with the shifted values
+ */
+std::vector<int32_t> shift_right(const std::vector<int32_t> &array,
+                                 size_t shift) {
+    if (array.size() <= shift) {
+        return {};  ///< We got an invalid shift, return empty array
+    }
+    std::vector<int32_t> res(array.size());  ///< Result array
+    for (size_t i = shift; i < array.size(); i++) {
+        res[i] = array[i - shift];  ///< Add values after the shift index
+    }
+    for (size_t i = 0; i < shift; i++) {
+        res[i] =
+            array[array.size() - shift + i];  ///< Add the values from the start
+    }
+    return res;
+}
+
+}  // namespace operations_on_datastructures
+
+/**
+ * @namespace tests
+ * @brief Testcases to check Union of Two Arrays.
+ */
+namespace tests {
+using operations_on_datastructures::print;
+using operations_on_datastructures::shift_right;
+/**
+ * @brief A Test to check an simple case
+ * @returns void
+ */
+void test1() {
+    std::cout << "TEST CASE 1\n";
+    std::cout << "Initialized arr = {1, 2, 3, 4, 5}\n";
+    std::cout << "Expected result: {4, 5, 1, 2, 3}\n";
+    std::vector<int32_t> arr = {1, 2, 3, 4, 5};
+    std::vector<int32_t> res = shift_right(arr, 2);
+    std::vector<int32_t> expected = {4, 5, 1, 2, 3};
+    assert(res == expected);
+    print(res);  ///< Should print 4 5 1 2 3
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check an empty vector
+ * @returns void
+ */
+void test2() {
+    std::cout << "TEST CASE 2\n";
+    std::cout << "Initialized arr = {}\n";
+    std::cout << "Expected result: {}\n";
+    std::vector<int32_t> arr = {};
+    std::vector<int32_t> res = shift_right(arr, 2);
+    std::vector<int32_t> expected = {};
+    assert(res == expected);
+    print(res);  ///< Should print empty newline
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check an invalid shift value
+ * @returns void
+ */
+void test3() {
+    std::cout << "TEST CASE 3\n";
+    std::cout << "Initialized arr = {1, 2, 3, 4, 5}\n";
+    std::cout << "Expected result: {}\n";
+    std::vector<int32_t> arr = {1, 2, 3, 4, 5};
+    std::vector<int32_t> res = shift_right(arr, 7);  ///< 7 > 5
+    std::vector<int32_t> expected = {};
+    assert(res == expected);
+    print(res);  ///< Should print empty newline
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check a very large input
+ * @returns void
+ */
+void test4() {
+    std::cout << "TEST CASE 4\n";
+    std::cout << "Initialized arr = {2, 4, ..., 420}\n";
+    std::cout << "Expected result: {420, 2, 4, ..., 418}\n";
+    std::vector<int32_t> arr;
+    for (int i = 1; i <= 210; i++) {
+        arr.push_back(i * 2);
     }
-    cout << "Your rotated array is=\t";
-    for (int i = 0; i < n; i++) {
-        cout << a[i] << " ";
+    print(arr);
+    std::vector<int32_t> res = shift_right(arr, 1);
+    std::vector<int32_t> expected;
+    expected.push_back(420);
+    for (int i = 0; i < 209; i++) {
+        expected.push_back(arr[i]);
     }
+    assert(res == expected);
+    print(res);  ///< Should print {420, 2, 4, ..., 418}
+    std::cout << "TEST PASSED!\n\n";
+}
+/**
+ * @brief A Test to check a shift of zero
+ * @returns void
+ */
+void test5() {
+    std::cout << "TEST CASE 5\n";
+    std::cout << "Initialized arr = {1, 2, 3, 4, 5}\n";
+    std::cout << "Expected result: {1, 2, 3, 4, 5}\n";
+    std::vector<int32_t> arr = {1, 2, 3, 4, 5};
+    std::vector<int32_t> res = shift_right(arr, 0);
+    assert(res == arr);
+    print(res);  ///< Should print 1 2 3 4 5
+    std::cout << "TEST PASSED!\n\n";
+}
+}  // namespace tests
+
+/**
+ * @brief Function to test the correctness of shift_right() function
+ * @returns void
+ */
+static void test() {
+    tests::test1();
+    tests::test2();
+    tests::test3();
+    tests::test4();
+    tests::test5();
+}
+
+/**
+ * @brief main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+    return 0;
 }