Merge Two Sorted List

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

Tag
LinkedList
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Easy Solution
Create a dummy node at head, convenient for creating a new linked list
/**
* @param {ListNode} l1
* @param {ListNode} l2
* @return {ListNode}
*/
var mergeTwoLists = function (l1, l2) {
var start1 = l1, start2 = l2;
var ret = [];

while (start1 && start2) {
if (start1.val < start2.val) {
ret.push(start1.val);
start1 = start1.next;
} else {
ret.push(start2.val);
start2 = start2.next;
}
}

while (start1) {
ret.push(start1.val);
start1 = start1.next;
}

while (start2) {
ret.push(start2.val);
start2 = start2.next;
}

return ret;
};