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[leetcode]Add Two Numbers @ Python

原题地址:https://oj.leetcode.com/problems/add-two-numbers/

题意:

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

解题思路:链表的基本操作。Two methods are provided. Method 1 is much slimmer

# Definition for singly-linked list.# class ListNode:#     def __init__(self, x):#         self.val = x#         self.next = Noneclass Solution:    # @return a ListNode    def addTwoNumbers(self, l1, l2):        # method 1: 14 Lines        dummy, flag = ListNode(0), 0        head = dummy        while flag or l1 or l2:            node = ListNode(flag)            if l1:                node.val += l1.val                l1 = l1.next            if l2:                node.val += l2.val                l2 = l2.next            flag = node.val / 10            node.val %= 10            head.next = node              head = head.next  # head.next, head = node, node        return dummy.next                """        # method 2: 24 Lines        if not l1: return l2        if not l2: return l1        dummy = ListNode(0)        p = dummy        flag = 0        while l1 and l2:            tmp = l1.val + l2.val + flag            p.next = ListNode( tmp % 10 )            flag = tmp / 10            l1, l2, p = l1.next, l2.next, p.next        if l1:            while l1:                tmp = l1.val + flag                p.next = ListNode( tmp % 10 )                flag = tmp / 10                l1, p = l1.next, p.next        if l2:            while l2:                tmp = l2.val + flag                p.next = ListNode( tmp % 10 )                flag = tmp / 10                l2, p = l2.next, p.next        if flag == 1: p.next = ListNode(flag)        return dummy.next        """

 

[leetcode]Add Two Numbers @ Python