feat: merge sort

Author: sl1673495

merge-sort.js

@@ -0,0 +1,39 @@
+function mergeSort(arr) {
+  var l = arr.length;
+  if (l === 1) return arr;
+  var m = Math.round(l / 2);
+  var left = arr.slice(0, m);
+  var right = arr.slice(m);
+  return merge(mergeSort(left), mergeSort(right));
+}
+
+function merge(arr1, arr2) {
+  var l1 = arr1.length;
+  var l2 = arr2.length;
+  var i1 = 0;
+  var i2 = 0;
+  var r = [];
+  while (i1 < l1 && i2 < l2) {
+    var item1 = arr1[i1];
+    var item2 = arr2[i2];
+    if (item1 < item2) {
+      r.push(item1);
+      i1++;
+    } else {
+      r.push(item2);
+      i2++;
+    }
+  }
+
+  while (i1 < l1) {
+    r.push(arr1[i1++]);
+  }
+
+  while (i2 < l2) {
+    r.push(arr2[i2++]);
+  }
+
+  return r;
+}
+
+console.log(mergeSort([1, 4, 2, 3, 5, 2, 7, 3, 17, 25, 19]))