分析

代码

/** * @param {ListNode} l1 * @param {ListNode} l2 * @return {ListNode} */var addTwoNumbers=function(l1, l2) {    let dummyHead = new ListNode(0), node=dummyHead;    let overflow=0, a, b, c, val;    while(l1!==null || l2!==null) {        a=(l1===null)?0:l1.val;        b=(l2===null)?0:l2.val;        c=a+b+overflow;        val=c%10;        overflow=Math.floor(c/10);        node.next=new ListNode(val);        node=node.next;        if(l1!==null) l1=l1.next;        if(l2!==null) l2=l2.next;    }    if(overflow!==0) {        node.next=new ListNode(overflow);    }    return dummyHead.next;}