New Feature - added [countingSort] algorithm.

algorithms/sorting/countingSort.js

@@ -0,0 +1,56 @@
+/**
+ * Counting Sort
+ *
+ * programiz.com
+ * https://www.programiz.com/dsa/counting-sort#:~:text=Counting%20sort%20is%20a%20sorting,index%20of%20the%20auxiliary%20array.
+ *
+ */
+
+/**
+ * Counting Sort is a simple sorting algorithm. It works by counting the
+ * number of occurrences of each element in the array.
+ * The Count of each element is stored and used to compute every item´s
+ * index in the sorted array
+ */
+
+/**
+ * Algorithm:
+ * To sort an array of size n in ascending order
+ * 1.Initialize a count array from 0 to n with values 0
+ * 2.Iterate through the array and save every occurrence of each element in the count array
+ * 3.Write each element in a new array matching the occurrences saved in count
+ */
+
+function countingSort(arr) {
+  let sortedArray = [];
+  let max = Math.max(...arr);
+  let count = [];
+
+  //initialization of count array from 0 to n
+  for (let i = 0; i <= max; i++) {
+    count[i] = 0;
+  }
+
+  //count occurrence of each element by iterating through the list
+  for (let i = 0; i < arr.length; i++) {
+    j = arr[i];
+    count[j]++;
+  }
+
+  //write elements into new array
+  let i = 0;
+  for (let j = 0; j <= max; j++) {
+    //iterate through count array
+    if (count[j] > 0) {
+      for (let k = 0; k < count[j]; k++) {
+        //write element into sortedArray
+        sortedArray[i] = j;
+        i++;
+      }
+    }
+  }
+  return sortedArray;
+}
+
+let arr = [1, 0, 1, 2, 4, 6, 8, 2];
+console.log(countingSort(arr)); //expected output:[0,1,1,2,2,4,6,8]