merge two sorted lists solution

Author: yoon-turtle

merge-two-sorted-lists/yoonthecoder.js

@@ -0,0 +1,25 @@
+var mergeTwoLists = function (list1, list2) {
+  // create a placeholder node and use it as a starting point
+  let placeholder = { val: -1, next: null };
+  let current = placeholder;
+
+  // loop through the lists until one of them is fully traversed
+  while (list1 !== null && list2 !== null) {
+    if (list1.val <= list2.val) {
+      // connect the element of list1 with the current node
+      current.next = list1;
+      // move list1 to its next node
+      list1 = list1.next;
+    } else {
+      current.next = list2;
+      list2 = list2.next;
+    }
+    // move the current pointer to the newly added node
+    current = current.next;
+  }
+  current.next = list1 !== null ? list1 : list2;
+  return placeholder.next;
+};
+
+// Time Complexity: O(n+m);
+// Space Complexity: O(1)