题解 | #链表相加(二)#

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 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
     */
    public ListNode addInList (ListNode head1, ListNode head2) {
        // write code here
        Stack<ListNode> stack1 = new Stack<ListNode>();
        Stack<ListNode> stack2 = new Stack<ListNode>();
        Stack<ListNode> stack = new Stack<ListNode>();
        int value = 0;
        int flag = 0;
        ListNode head = null;
        ListNode temp = null;
        boolean b = true;
        while(head1 != null){
            stack1.push(head1);
            head1 = head1.next;
        }
        while(head2 != null){
            stack2.push(head2);
            head2 = head2.next;
        }
        while(!stack1.isEmpty() && !stack2.isEmpty()){
            value = stack1.pop().val + stack2.pop().val;
            stack.push(new ListNode((value + flag)%10));
            flag = (value+flag) / 10;
        }
        while(!stack1.isEmpty()){
            value = stack1.pop().val + flag;
            stack.push(new ListNode(value%10));
            flag = value/10;
        }
        while(!stack2.isEmpty()){
            value = stack2.pop().val + flag;
            stack.push(new ListNode(value%10));
            flag = value/10;
        }
        while(!stack.isEmpty()){
            if(b){
                head = stack.pop();
                temp = head;
                b = false;
                continue;
            }
            temp.next = stack.pop();
            temp = temp.next;
        }
        return head;
    }
}