leetcode2-LeetCode.swift:从前有一个算法菜鸟，他对Swift略知一二

leetcode 2 LeetCode.swift 愚者千焦，必有得。 作为算法的白痴，我大胆解决. 上的问题，尤其是. 大多数算法不是我自己想出来的。 let :smiling_face_with_sunglasses: = " Easy " , :neutral_face: = " Medium " , :fearful_face: = " Hard " , :Japanese_secret_button: = " require premium membership " 1 :smiling_face_with_sunglasses: 2 :neutral_face: 3 :neutral_face: 4 :fearful_face: 5 :neutral_face: 6 :neutral_face: 7 :smiling_face_with_sunglasses: 8 :neutral_face: 9 :smiling_face_with_sunglasses: 10 :fearful_face: 11 :neutral_face: 12 :neutral_face: 13 :smiling_face_with_sunglasses: 14 :smiling_face_with_sunglasses: 15 :neutral_face: 16 :neutral_face: 17 :neutral_face: 18 :neutral_face: 19 :neutral_face: 20 :smiling_face_with_sunglasses: 21 :smiling_face_with_sunglasses: 22 :neutral_face: 23 :fearful_face: 24 :neutral_face: 25 :fearful_face: 26 :smiling_face_with_sunglasses: 27 :smiling_face_with_sunglasses: 28 :smiling_face_with_sunglasses: 29 :neutral_face: 30 :fearful_face: 31 :neutral_face: 32 :fearful_face: 33 :neutral_face: 34 :neutral_face: 35 :smiling_face_with_sunglasses: 36 :neutral_face: 37 :fearful_face: 38 :smiling_face_with_sunglasses: 39 :neutral_face: 40 :neutral_face: 41 :fearful_face: 42 :fearful_face: 43 :neutral_face: 44 :fearful_face: 45 :fearful_face: 46 :neutral_face: 47 :neutral_face: 48 :neutral_face: 49 :neutral_face: 50 :neutral_face: 51 :fearful_face: 52 :fearful_face: 53 :smiling_face_with_sunglasses: 54 :neutral_face: 55 :neutral_face: 56 :neutral_face: 57 :fearful_face: 58 :smiling_face_with_sunglasses: 59 :neutral_face: 60 :neutral_face: 61 :neutral_face: 62 :neutral_face: 63 :neutral_face: 64 :neutral_face: 65 :fearful_face: 66 :smiling_face_with_sunglasses: 67 :smiling_face_with_sunglasses: 68 :fearful_face: 69 :smiling_face_with_sunglasses: