feat: CountingSort implementation (#5287)

* feat: CountingSort

* checkstyle: fix formatting

* refactor: adding additional final modifiers

* refactor: restructure sorting, update docs and tests

* docs: typo fix

---------

Co-authored-by: Alex Klymenko <alx@alx.com>
Co-authored-by: Piotr Idzik <65706193+vil02@users.noreply.github.com>

src/main/java/com/thealgorithms/sorts/CountingSort.java

@@ -0,0 +1,60 @@
+package com.thealgorithms.sorts;
+
+import java.util.Arrays;
+
+/**
+ * A standard implementation of the Counting Sort algorithm for integer arrays.
+ * This implementation has a time complexity of O(n + k), where n is the number
+ * of elements in the input array and k is the range of the input.
+ * It works only with integer arrays.
+ *
+ * The space complexity is O(k), where k is the range of the input integers.
+ *
+ * Note: This implementation handles negative integers as it
+ * calculates the range based on the minimum and maximum values of the array.
+ *
+ */
+public final class CountingSort {
+    private CountingSort() {
+    }
+
+    /**
+     * Sorts an array of integers using the Counting Sort algorithm.
+     *
+     * @param array the array to be sorted
+     * @return the sorted array
+     */
+    public static int[] sort(int[] array) {
+        if (array.length == 0) {
+            return array;
+        }
+        final var stats = Arrays.stream(array).summaryStatistics();
+        final int min = stats.getMin();
+        int[] count = computeHistogram(array, min, stats.getMax() - min + 1);
+        toCumulative(count);
+        return reconstructSorted(count, min, array);
+    }
+
+    private static int[] computeHistogram(final int[] array, final int shift, final int spread) {
+        int[] res = new int[spread];
+        for (final var value : array) {
+            res[value - shift]++;
+        }
+        return res;
+    }
+
+    private static void toCumulative(int[] count) {
+        for (int i = 1; i < count.length; i++) {
+            count[i] += count[i - 1];
+        }
+    }
+
+    private static int[] reconstructSorted(final int[] cumulativeCount, final int shift, final int[] array) {
+        int[] res = new int[array.length];
+        for (int i = array.length - 1; i >= 0; i--) {
+            res[cumulativeCount[array[i] - shift] - 1] = array[i];
+            cumulativeCount[array[i] - shift]--;
+        }
+        return res;
+    }
+}