题解 | #链表相加(二)#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
#include <deque>
#include<stack>
#include<iostream>

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head1 ListNode类 
     * @param head2 ListNode类 
     * @return ListNode类
     */
    ListNode* addInList(ListNode* head1, ListNode* head2) {
        // write code here
        if (head1 == nullptr) {
            return head2;
        }

        if (head2 == nullptr) {
            return head1;
        }

        stack<ListNode*> stackA;
        stack<ListNode*> stackB;

        ListNode* pNode1 = head1;
        ListNode* pNode2 = head2;

        while (pNode1 != nullptr) {
            stackA.push(pNode1);
            pNode1 = pNode1->next;
        }

        while (pNode2 != nullptr) {
            stackB.push(pNode2);
            pNode2 = pNode2->next;
        }

        int carry = 0;
        ListNode* SumListHead = nullptr;

        while (!stackA.empty() || !stackB.empty()) {
            int val_A = 0;
            int val_B = 0;
            if (!stackA.empty()) {
                val_A = stackA.top()->val;
                stackA.pop();
            }
            if (!stackB.empty()) {
                val_B = stackB.top()->val;
                stackB.pop();
            }

            int val = val_A + val_B + carry;
            carry = val / 10;
            val = val % 10;

            ListNode* pnode = new ListNode(val);
            pnode->next = SumListHead;
            SumListHead = pnode;
        }

        if (carry != 0) {
            ListNode* pnode = new ListNode(carry);
            pnode->next = SumListHead;
            SumListHead = pnode;
        }
        
        return SumListHead;
    }
};