算法总结之 两个单链表生成相加的链表

Posted 2020-10-06

 对于这个问题还有一个很好的方法：

1、将两个链表逆序，这样就可以依次得到从低到高位的数字

2、同步遍历两个逆序后链表，相加生成新链表，同时关注进位

3、当两个链表都遍历完成后，关注进位。

4、 将两个逆序的链表再逆序一遍，调整回去

返回结果链表

package TT;

public class Test98 {

    public class Node{
        
        public int value;
        public Node next;
        
        public Node(int data){
            this.value=data;
        }
        
        
    }
    

    public  Node addLists2(Node head1, Node head2){
        head1 = reverseList(head1);
        head2 = reverseList(head2);
        
        int ca = 0;
        int n1 =0;
        int n2 =0;
        int n =0;
         
        Node c1 = head1;
        Node c2 = head2;
        Node node = null;
        Node pre = null;
        
        while(c1 !=null || c2!=null){
            n1 = c1 != null ? c1.value:0;
            n2 = c2 != null ? c2.value:0;
            n = n1+n2+ca;
            pre= node;
            node = new Node(n % 10);
            node.next=pre;
            ca=n/10;
            c1=c1 != null ? c1.next : null;
            c2=c2 != null ? c2.next : null;
        }
        if(ca == 1){
            pre=node;
            node = new Node(1);
            node.next = pre;    
        }
        reverseList(head1);
        reverseList(head2);
        return node;
    }
       public  static  Node reverseList(Node head){
            Node pre = null;
            Node next = null;
            while(head!=null){
                next=head.next;
                head.next=pre;
                pre=head;
                head=next;
            }
            return pre;
       }
    
        
    
    
}