Merge sort algorithm

Author: dhimasanb

Algorithm/mergeSort.js

@@ -0,0 +1,24 @@
+function mergeSort(arr) {
+  if (arr.length < 2) return arr;
+  let middleIndex = Math.floor(arr.length / 2);
+  let firstHalf = arr.slice(0, middleIndex);
+  let secondHalf = arr.slice(middleIndex);
+
+  return merge(mergeSort(firstHalf), mergeSort(secondHalf));
+}
+
+function merge(arr1, arr2) {
+  let result = [];
+  while (arr1.length && arr2.length) {
+    let minElem;
+    if (arr1[0] < arr2[0]) minElem = arr1.shift();
+    else minElem = arr2.shift();
+    result.push(minElem);
+  }
+
+  if (arr1.length) result = result.concat(arr1);
+  else result = result.concat(arr2);
+  return result;
+}
+
+mergeSort([6000, 34, 203, 3, 746, 200, 984, 198, 764, 1, 9, 1]); // [ 1, 1, 3, 9, 34, 198, 200, 203, 746, 764, 984, 6000 ]