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71 lines
1.6 KiB
Python
71 lines
1.6 KiB
Python
"""
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2. Add Two Numbers
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Difficulty: Medium
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https://leetcode.com/problems/add-two-numbers/
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──────────────────────────────────────────────────
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You are given two non-empty linked lists representing two
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non-negative integers. The digits are stored in reverse order, and
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each of their nodes contains a single digit. Add the two numbers and
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return the sum as a linked list.
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You may assume the two numbers do not contain any leading zero,
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except the number 0 itself.
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Example 1:
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Input: l1 = [2,4,3], l2 = [5,6,4]
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Output: [7,0,8]
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Explanation: 342 + 465 = 807.
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Example 2:
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Input: l1 = [0], l2 = [0]
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Output: [0]
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Example 3:
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Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
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Output: [8,9,9,9,0,0,0,1]
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Constraints:
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• The number of nodes in each linked list is in the range [1, 100].
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• 0 <= Node.val <= 9
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• It is guaranteed that the list represents a number that does not
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have leading zeros.
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"""
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# Definition for singly-linked list.
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# class ListNode:
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# def __init__(self, val=0, next=None):
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# self.val = val
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# self.next = next
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class Solution:
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def addTwoNumbers(
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self, l1: Optional[ListNode], l2: Optional[ListNode]
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) -> Optional[ListNode]:
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dummy = ListNode()
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carry = 0
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curr = dummy
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while l1 or l2 or carry:
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s = (l1.val if l1 else 0) + (l2.val if l2 else 0) + carry
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carry, val = divmod(s, 10)
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curr.next = ListNode(val)
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curr = curr.next
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l1 = l1.next if l1 else None
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l2 = l2.next if l2 else None
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return dummy.next
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