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iOS 面试题（13）：求两个链表表示的数的和
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| // Author: Tang Qiao | |
| // GitHub: https://github.com/tangqiaoboy | |
| // | |
| // Add Two Numbers | |
| // https://leetcode.com/problems/add-two-numbers/ | |
| private class ListNode { | |
| public var val: Int | |
| public var next: ListNode? | |
| public init(_ val: Int) { | |
| self.val = val | |
| self.next = nil | |
| } | |
| } | |
| private class Solution { | |
| private static func getNodeValue(_ node: ListNode?) -> Int { | |
| return node.flatMap { $0.val } ?? 0 | |
| } | |
| func addTwoNumbers(_ l1: ListNode?, _ l2: ListNode?) -> ListNode? { | |
| if l1 == nil || l2 == nil { | |
| return l1 ?? l2 | |
| } | |
| var p1 = l1 | |
| var p2 = l2 | |
| let result: ListNode? = ListNode(0) | |
| var current = result | |
| var extra = 0 | |
| while p1 != nil || p2 != nil || extra != 0 { | |
| var tot = Solution.getNodeValue(p1) + | |
| Solution.getNodeValue(p2) + extra | |
| extra = tot / 10 | |
| tot = tot % 10 | |
| let sum:ListNode? = ListNode(tot) | |
| current!.next = sum | |
| current = sum | |
| p1 = p1.flatMap { $0.next } | |
| p2 = p2.flatMap { $0.next } | |
| } | |
| return result!.next | |
| } | |
| } | |
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