题解 | BM11 链表相加(二)

/*
 * function ListNode(x){
 *   this.val = x;
 *   this.next = null;
 * }
 */

/**
 * 
 * @param head1 ListNode类 
 * @param head2 ListNode类 
 * @return ListNode类
 */
function addInList(head1, head2) {
    // write code here
    // 获取反转数组
    function getInv(head) {
        let end = head;
        cur = head;
        pre = null;
        while (end) {
            end = end.next;
        }
        while (cur != end) {
            let temp = cur.next;
            cur.next = pre;
            pre = cur;
            cur = temp;
        }
        return pre;
    }
    // 先反转一下两个列表，方便进行累加操作
    let a = getInv(head1);
    let b = getInv(head2);
    let list = new ListNode(0);
    let ans = list;
    let c = 0;
    while (a || b) {
        list.next = new ListNode(0);
        list = list.next;
        let x = 0, y = 0;
        if (a != null) {
            x = a.val;
            a = a.next;
        }
        if (b != null) {
            y = b.val;
            b = b.next;
        }
        let sum = x + y + c;
        if (sum > 9) {
            c = parseInt(sum / 10);
            sum = sum % 10;
        } else {
            c = 0;
        }
        list.val = sum;
    }
    // 反转最终结果列表
    ans = getInv(ans.next);
    // console.log("ans:", ans);
    return ans;
}
module.exports = {
    addInList: addInList
};