Short List problem solved

Author: hasibulislam999

Merge Sort/148_sort-list.js

@@ -0,0 +1,72 @@
+/**
+ * Title: Sort List
+ * Description: Given the head of a linked list, return the list after sorting it in ascending order.
+ * Author: Hasibul Islam
+ * Date: 10/04/2023
+ */
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @return {ListNode}
+ */
+var sortList = function (head) {
+  let groupSize = 1;
+  let nodeCount = Infinity;
+  let count = 0;
+
+  const sortedHead = { next: head };
+
+  while (groupSize < nodeCount) {
+    let group1Head = sortedHead.next;
+    let group2Head = sortedHead.next;
+    let groupTail = sortedHead;
+
+    while (group1Head) {
+      let groupCount = 0;
+
+      while (group2Head && groupCount < groupSize) {
+        groupCount++;
+        group2Head = group2Head.next;
+      }
+
+      let group1Used = 0;
+      let group2Used = 0;
+
+      while (
+        (group1Head && group1Used < groupSize) ||
+        (group2Head && group2Used < groupSize)
+      ) {
+        if (
+          !group2Head ||
+          group2Used >= groupSize ||
+          (group1Used < groupSize && group1Head.val < group2Head.val)
+        ) {
+          groupTail.next = group1Head;
+          group1Head = group1Head.next;
+          group1Used++;
+        } else {
+          groupTail.next = group2Head;
+          group2Head = group2Head.next;
+          group2Used++;
+        }
+        groupTail = groupTail.next;
+        count++;
+      }
+
+      group1Head = group2Head;
+      groupTail.next = group2Head;
+    }
+
+    groupSize *= 2;
+    if (nodeCount === Infinity) nodeCount = count;
+  }
+
+  return sortedHead.next;
+};