剑指offer（16）合并两个排序的链表

/*function ListNode(x){
    this.val = x;
    this.next = null;
}*/
function Merge(pHead1, pHead2)
{
    // write code here
    if(pHead1 == null && pHead2 == null){
        return null;
    }
    if(pHead1 == null){
        return pHead2;
    }
    if(pHead2 == null){
        return pHead1;
    }
    var newHead = null;
    if(pHead1.val <= pHead2.val){
        newHead = pHead1;
        newHead.next = Merge(pHead1.next,pHead2);
    }
    else{
        newHead = pHead2;
        newHead.next = Merge(pHead1,pHead2.next);
    }
    return newHead;
}