LeetCode——Add Two Numbers

Add Two Numbers

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

中文：給你兩個包含非負數的鏈表。數字以倒序存放，每個節點只包含一個數字。把兩個鏈表加起來，返回一個單鏈表。

輸入: (2 -> 4 -> 3) + (5 -> 6 -> 4)
輸出: 7 -> 0 -> 8

public class AddTwoNumbers {

	public ListNode addTwoNumbers(ListNode l1, ListNode l2){
		ListNode result = new ListNode(0);
		ListNode temp = result;
		int sum = 0;
		while(l1 != null || l2 != null){
			if(l1 != null){
				sum += l1.val;
				l1 = l1.next;
			}
			if(l2 != null){
				sum += l2.val;
				l2 = l2.next;
			}
			//對10取余，判斷兩數之和是否大於10
			temp.next = new ListNode(sum%10);
			temp = temp.next;
			//取進位的數，值為0,1
			sum /= 10;
		}
		if(sum >0)
			temp.next = new ListNode(sum);
		return result.next;
	}
	  // Definition for singly-linked list.
	  public class ListNode {
	      int val;
	      ListNode next;
	      ListNode(int x) {
	          val = x;
	          next = null;
	      }
	  }
	public static void main(String[] args) {
		new AddTwoNumbers().run();
	}
	public  void run(){
		ListNode l1 = new ListNode(2);
		l1.next = new ListNode(4);
		l1.next.next = new ListNode(3);
		
		ListNode l2 = new ListNode(5);
		l2.next = new ListNode(6);
		l2.next.next = new ListNode(4);
		
		ListNode ret = addTwoNumbers(l1,l2);
		
		System.out.println(ret.val);
		System.out.println(ret.next.val);
		System.out.println(ret.next.next.val);
	}
}