【LeetCode】Add Two Numbers

标签：leetcode   链表   合并   

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

思路：链表的合并

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        if (l1 == null) {
			return l2;
		}
		if (l2 == null) {
			return l1;
		}
		ListNode head = null;
		ListNode tail = null;
		ListNode p1 = l1;
		ListNode p2 = l2;
		int sum , borrow = 0;
	
		while(p1 != null && p2 != null)
		{
			sum = p1.val + p2.val + borrow;
			borrow = sum >= 10?1:0;
			sum -= 10*borrow;
			if (head == null) {
				head = new ListNode(sum);
				tail = head;
			}
			else {
				ListNode cur = new ListNode(sum);
				tail.next = cur;
				tail = cur;
			}
			p1 = p1.next;
			p2 = p2.next;
			
		}
		while(p1 != null)
		{
			sum = p1.val + borrow;
			borrow = sum >= 10?1:0;
			sum -= 10*borrow;
			ListNode cur = new ListNode(sum);
			tail.next = cur;
			tail = cur;
			p1 = p1.next;
		}
		while(p2 != null)
		{
			sum = p2.val + borrow;
			borrow = sum >= 10?1:0;
			sum -= 10*borrow;
			ListNode cur = new ListNode(sum);
			tail.next = cur;
			tail = cur;
			p2 = p2.next;
		}
		if (borrow == 1) {
			ListNode cur = new ListNode(1);
			tail.next = cur;
		}
		return head;
    }
}

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【LeetCode】Add Two Numbers

标签：leetcode   链表   合并   

原文地址：http://blog.csdn.net/xiaozhuaixifu/article/details/26281993