2.两数相加

2.两数相加

class ListNode {
    constructor(val, next) {
        this.val = (val === undefined ? 0 : val)
        this.next = (next === undefined ? null : next)
    }
}
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var addTwoNumbers = function(l1, l2) {
    let p1=l1
    let p2=l2
    let arr=[]
    let carry=0 // 进位
    while(p1||p2){
        let current1=p1?p1.val:0
        let current2=p2?p2.val:0
        let sun=current1+current2+carry
        carry=Math.floor(sun/10)
        arr.push(sun%10)
        if(p1)p1=p1.next
        if(p2)p2=p2.next
    }
    if(carry)arr.push(carry)
    return buildLinkedList(arr)
};
// up time:6ms  space:56mb


// 4ms 56mb
var addTwoNumbersSimple = function(l1, l2) {
    let head = new ListNode(0)
    let p1=l1
    let p2=l2
    let p3=head
    let carry=0 // 进位
    while(p1||p2){
        let current1=p1?p1.val:0
        let current2=p2?p2.val:0
        let sun=current1+current2+carry
        carry=Math.floor(sun/10)
        p3.next=new ListNode(sun%10)
        if(p1)p1=p1.next
        if(p2)p2=p2.next
        p3=p3.next
    }
    // 处理最高位
    if(carry) p3.next=new ListNode(carry)
    return head.next
};

let a1 = [9,9,9,9,9,9,9], a2 = [9,9,9,9]
let l1= buildLinkedList(a1);
let l2= buildLinkedList(a2);
console.log(addTwoNumbers(l1, l2));

function buildLinkedList(arr) {
    let head = new ListNode(0);
    let p = head;
    for (let i = 0; i < arr.length; i++) {
        p.next = new ListNode(arr[i]);
        p = p.next;
    }
    return head.next;
}

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