KrauserHuang

class Solution {
  func removeElement(_ nums: [Int], val: Int) -> Int {
    // filter可以篩選目標數字，$0代表nums陣列的每一個數字，篩選條件是當數字不等於val則留下，最後回傳剩餘nums的總數
    nums = nums.filter { $0 != val }
    return nums.count
  }
}

KrauserHuang

func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
    // 拿來儲存數字(Key)對應的index(Value)
    var dict = [Int: Int]()
    /*
     nums.enumerated()結果
     (0, 2)
     (1, 7)
     (2, 11)
     (3, 15)
     */

KrauserHuang

// left | right | root
func postOrderTraverse(_ root: Node?) {
    if let root = root {
        postOrderTraverse(root.left)
        postOrderTraverse(root.right)
        print(root.value, terminator: " ")
    }
}
postOrderTraverse(node_1)

KrauserHuang

// root | left | right
func preOrderTraverse(_ root: Node?) {
    if let root = root {
        print(root.value, terminator: " ")
        preOrderTraverse(root.left)
        preOrderTraverse(root.right)
    }
}
preOrderTraverse(node_1)

KrauserHuang

// left | root | right
func inOrderTraverse(_ root: Node?) {
    if let root = root {
        inOrderTraverse(root.left)
        print(root.value, terminator: " ")
        inOrderTraverse(root.right)
    }
}
inOrderTraverse(node_1)

KrauserHuang

import Foundation

public class Node {
    var value: Int
    var left: Node?
    var right: Node?
    
    public init(_ value: Int) {
        self.value = value
    }

KrauserHuang

let nestedGroup = NSCollectionLayoutGroup.vertical(layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1),
                                                                                      heightDimension: .fractionalWidth(16/9)),
                                                   subitems: [fullPhotoItem, mainWithPairGroup, tripletGroup, mainWithPairReversedGroup]

KrauserHuang

let mainWithPairReversedGroup = NSCollectionLayoutGroup.horizontal(layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1),
                                                                                                      heightDimension: .fractionalWidth(4/9)),
                                                                   subitems: [trailingGroup, mainItem])

KrauserHuang

let tripleItem = NSCollectionLayoutItem(layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1/3),
                                                                           heightDimension: .fractionalHeight(1))
                                        
tripleItem.contentInsets = NSDirectionalEdgeInsets(top: 2, leading: 2, bottom: 2, trailing: 2)
                                        
let tripletGroup = NSCollectionLayoutGroup.horizontal(layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1),
                                                                                         heightDimension: .fractionalWidth(2/9)),
                                                      subitem: tripleItem,
                                                      count: 3)

KrauserHuang

let mainItem = NSCollectionLayoutItem(layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(2/3),
											                                                   heightDimension: .fractionalHeight(1.0))
                                      
mainItem.contentInsets = NSDirectionalEdgeInsets(top: 2, leading: 2, bottom: 2, trailing: 2)
                                      
let pairItem = NSCollectionLayoutItem(layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1/3),
                                                                         heightDimension: .fractionalHeight(1/2))
                                      
pairItem.contentInsets = NSDirectionalEdgeInsets(top: 2, leading: 2, bottom: 2, trailing: 2)