将两个链表的长度变成一样

链表1到结尾处继续遍历链表2，链表2到结尾处继续遍历链表1，在遍历的同时比较节点是否相同

function ListNode(x){
    this.val = x;
    this.next = null;
}
function FindFirstCommonNode(pHead1, pHead2)
{
    // write code here
    let head1 = pHead1;
    let head2 = pHead2;
    while (head1 !== head2) {
        if (head1 == null) {
            head1 = pHead2;
        } else {
            head1 = head1.next;
        }
        if (head2 == null) {
            head2 = pHead1;
        } else {
            head2 = head2.next;
        }
    }
    return head1
}
module.exports = {
    FindFirstCommonNode : FindFirstCommonNode
};