feat : added counting sort method (#170)

* feat : added counting sort method

* Remove some unnecessary colons

---------

Co-authored-by: madhuredra <madhuredra.tiwari@zemosolabs.com>
Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>

Author: 3 people

sorts/counting_sort.ts

@@ -0,0 +1,30 @@
+/**
+ * @author dev-madhurendra
+ * Counting sort is an algorithm for sorting a collection
+ * of objects according to keys that are small integers.
+ * @see https://en.wikipedia.org/wiki/Counting_sort
+ * @example
+ * const array = [3, 0, 2, 5, 4, 1]
+ * countingSort(array, 0, 5)
+ */
+  
+export const countingSort = (inputArr: number[], min: number, max: number) => {
+    const sortedArr = []
+    
+    const count = new Array(max - min + 1).fill(0)
+
+    for (let i = 0; i < inputArr.length; i++)
+      count[inputArr[i] - min]++
+
+    count[0] -= 1
+    
+    for (let i = 1; i < count.length; i++)
+      count[i] += count[i - 1]
+
+    for (let i = inputArr.length - 1; i >= 0; i--) {
+      sortedArr[count[inputArr[i] - min]] = inputArr[i]
+      count[inputArr[i] - min]--
+    }
+
+    return sortedArr
+  }

sorts/test/counting_sort.test.ts

@@ -0,0 +1,28 @@
+import { countingSort } from "../counting_sort";
+
+const testCases = [
+  [
+    [3, 0, 2, 5, 4, 1],
+    [0, 1, 2, 3, 4, 5],
+  ],
+  [
+    [6, 4, 2, 1, 3, 5],
+    [1, 2, 3, 4, 5, 6],
+  ],
+  [
+    [11, 14, 12, 15, 16, 13],
+    [11, 12, 13, 14, 15, 16],
+  ],
+  [
+    [13, 18, 2, 15, 43, 11],
+    [2, 11, 13, 15, 18, 43],
+  ],
+];
+
+it.each(testCases)(
+  'The countingSort of the array %p is %p',
+  (input, expected) => {
+    const res = countingSort(input, Math.min(...input), Math.max(...input));
+    expect(res).toEqual(expected);
+  }
+);