[Swift] LeetCode - 2. Add Two Numbers

문제: https://leetcode.com/problems/add-two-numbers/

Add Two Numbers - LeetCode

 

 

연결리스트 문제는 CustomStringConvertible을 익스텐션으로 해서 프린트해가며 풀고 있습니다. ㅎㅎ

import Foundation

public class ListNode {
    public var val: Int
    public var next: ListNode?
    public init() { self.val = 0; self.next = nil; }
    public init(_ val: Int) { self.val = val; self.next = nil; }
    public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
}

extension ListNode: CustomStringConvertible {
    public var description: String {
        var result = ""
        var current = self
        
        while current != nil {
            result.append("\(current.val)-> ")
            if current.next == nil {
                return result
            }
            current = current.next!
        }
        
        return result
    }
}

class Solution {
    func addTwoNumbers(_ l1: ListNode?, _ l2: ListNode?) -> ListNode? {
        var olim = 0
        var l1 = l1
        var l2 = l2
        let root = ListNode(0)
        var head = root
        
        while l1 != nil || l2 != nil ||  olim != 0 {
            var value = 0
            
            if l1 != nil {
                value += l1!.val
            }
            if l2 != nil {
                value += l2!.val
            }
            
            if olim != 0 {
                value += olim
                olim = 0
            }
            
            if value >= 10 {
                olim = value / 10
                value %= 10
            }
            
            head.next = ListNode(value)
            head = head.next!
            
            l1 = l1?.next
            l2 = l2?.next
        }
        
        return root.next
    }
}

let head1 = ListNode(9)
let node1 = ListNode(9)
let node2 = ListNode(9)
let node3 = ListNode(9)
let node4 = ListNode(9)
let node5 = ListNode(9)
let node6 = ListNode(9)
let node7 = ListNode(9)
head1.next = node1
node1.next = node2
node2.next = node3
node3.next = node4
node4.next = node5
node5.next = node6
node6.next = node7

let head2 = ListNode(9)
let node21 = ListNode(9)
let node22 = ListNode(9)
let node23 = ListNode(9)
let node24 = ListNode(9)
head2.next = node21
node21.next = node22
node22.next = node23
node23.next = node24

print(Solution().addTwoNumbers(head1, head2)) // [8,9,9,9,0,0,0,1]