[Swift]LeetCode67. 二进制求和 | Add Binary
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➤微信公众号：山青咏芝（shanqingyongzhi）
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➤GitHub地址：https://github.com/strengthen/LeetCode
➤原文地址：https://www.cnblogs.com/strengthen/p/9697968.html
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Given two binary strings, return their sum (also a binary string).
The input strings are both non-empty and contains only characters 1 or 0.
Example 1:
Input: a = "11", b = "1" Output: "100"
Example 2:
Input: a = "1010", b = "1011" Output: "10101"
给定两个二进制字符串，返回他们的和（用二进制表示）。
输入为非空字符串且只包含数字 1 和 0。
示例 1:
输入: a = "11", b = "1" 输出: "100"
示例 2:
输入: a = "1010", b = "1011" 输出: "10101"
12ms
1 class Solution {
2 func addBinary(_ a: String, _ b: String) -> String {
3 let charsA = Array(a)
4 let charsB = Array(b)
5 var ans = ""
6 var m = charsA.count - 1
7 var n = charsB.count - 1
8 var carry = false
9 while m >= 0 && n >= 0 {
10 if charsA[m] == "1" && charsB[n] == "1" {
11 if carry {
12 ans = "1" + ans
13 } else {
14 ans = "0" + ans
15 }
16 carry = true
17 } else if charsA[m] == "1" || charsB[n] == "1" {
18 if carry {
19 ans = "0" + ans
20 carry = true
21 } else {
22 ans = "1" + ans
23 carry = false
24 }
25 } else {
26 if carry {
27 ans = "1" + ans
28 } else {
29 ans = "0" + ans
30 }
31 carry = false
32 }
33 m -= 1
34 n -= 1
35 }
36 while m >= 0 {
37 if charsA[m] == "1" {
38 if carry {
39 ans = "0" + ans
40 } else {
41 ans = "1" + ans
42 }
43 } else {
44 if carry {
45 ans = "1" + ans
46 } else {
47 ans = "0" + ans
48 }
49 carry = false
50 }
51 m = m - 1
52 }
53 while n >= 0 {
54 if charsB[n] == "1" {
55 if carry {
56 ans = "0" + ans
57 } else {
58 ans = "1" + ans
59 }
60 } else {
61 if carry {
62 ans = "1" + ans
63 } else {
64 ans = "0" + ans
65 }
66 carry = false
67 }
68 n -= 1
69 }
70 if carry {
71 ans = "1" + ans
72 }
73 return ans
74 }
75 }16ms
1 class Solution {
2 func addBinary(_ a: String, _ b: String) -> String {
3 var lhs: [Character] = a.reversed()
4 var rhs: [Character] = b.reversed()
5 // zero padding
6 if lhs.count < rhs.count {
7 lhs.append(contentsOf: String(repeating: "0", count: rhs.count - lhs.count))
8 }
9 else if rhs.count < lhs.count {
10 rhs.append(contentsOf: String(repeating: "0", count: lhs.count - rhs.count))
11 }
12 // adding
13 let len = lhs.count
14 var step = 0
15 var result = ""
16 for i in 0..<len {
17 switch (lhs[i], rhs[i], step) {
18 case ("0", "0", 0):
19 result.append("0")
20 step = 0
21 case ("0", "0", 1):
22 fallthrough
23 case ("0", "1", 0):
24 fallthrough
25 case ("1", "0", 0):
26 result.append("1")
27 step = 0
28 case ("1", "1", 0):
29 fallthrough
30 case ("1", "0", 1):
31 fallthrough
32 case ("0", "1", 1):
33 result.append("0")
34 step = 1
35 case ("1", "1", 1):
36 result.append("1")
37 step = 1
38 default: fatalError()
39 }
40 }
41 if step == 1 {
42 result.append("1")
43 }
44 while result.last == "0" {
45 result.removeLast()
46 }
47 if result == "" {
48 result = "0"
49 }
50 return String(result.reversed())
51 }
52 }20ms
1 class Solution {
2 func StringToNum(_ s: String) -> Int {
3 var num = 0
4 for c in s.characters
5 {
6 var n = 0
7 if (c == "1") {
8 n = 1
9 }
10 num = num * 2 + n
11 }
12 return num
13 }
14
15 func NumToString(_ num_: Int) -> String {
16 if num_ == 0 {
17 return "0"
18 }
19
20 var num = num_
21 var str = ""
22 while num > 0 {
23 var n = num % 2
24 num /= 2
25 var s: String
26 if n == 0 {
27 s = "0"
28 }
29 else {
30 s = "1"
31 }
32 str = s + str
33 }
34
35 return str
36 }
37
38 func StringToArr(_ s: String) -> [Int] {
39 var nums: [Int] = [Int](repeating: 0, count:s.count)
40 var idx = nums.count - 1
41 for c in s.characters
42 {
43 var n = 0
44 if (c == "1") {
45 n = 1
46 }
47 nums[idx] = n
48 idx -= 1
49 }
50 return nums
51 }
52
53 func ArrToString(_ nums: [Int]) -> String {
54
55 var str = ""
56 for i in 0...nums.count - 1 {
57 if (!(i == nums.count - 1 && nums[i] == 0)) {
58 str = String(nums[i]) + str
59 }
60 }
61
62 return str
63 }
64
65 func ArrAdd(_ a: [Int], _ b: [Int]) -> [Int] {
66 var c_cnt = max(a.count, b.count) + 1;
67 var c: [Int] = [Int](repeating: 0, count: c_cnt)
68 var up = 0
69 for i in 0...c_cnt - 1 {
70 var sum = up
71 if (i < a.count) {
72 sum += a[i]
73 }
74 if (i < b.count) {
75 sum += b[i]
76 }
77 if sum >= 2 {
78 sum -= 2
79 up = 1
80 }
81 else {
82 up = 0
83 }
84 c[i] = sum
85 }
86 return c
87 }
88
89 func addBinary(_ a: String, _ b: String) -> String {
90 var aa = StringToArr(a)
91 var bb = StringToArr(b)
92 // print(aa,bb)
93 var cc = ArrAdd(aa,bb)
94 var c = ArrToString(cc)
95 print(c)
96
97 return c
98 }
99 }24ms
1 class Solution {
2 func addBinary(_ a: String, _ b: String) -> String {
3 var sum = 0, carry = 0, res = ""
4 let aChars = Array(a.characters), bChars = Array(b.characters)
5 var i = aChars.count - 1, j = bChars.count - 1
6
7 while i >= 0 || j >= 0 || carry > 0 {
8 sum = carry
9 if i >= 0 {
10 sum += Int(String(aChars[i]))!
11 i -= 1
12 }
13 if j >= 0 {
14 sum += Int(String(bChars[j]))!
15 j -= 1
16 }
17 carry = sum / 2
18 sum = sum % 2
19 res = String(sum) + res
20 }
21
22 return res
23 }
24 }28ms
1 class Solution {
2 //从最低位加到最高位，当前位相加结果是%2，进位是/2，
3 //记得处理每一次的进位和最后一次的进位，最后反向输出字符。
4 func addBinary(_ a: String, _ b: String) -> String {
5 //存储字符的输出变量
6 var str:String = String()
7 //获取a的字符数量
8 var i:Int = a.count-1
9 //获取b的字符数量
10 var j:Int = b.count-1
11 //进位标志
12 var carry:Int = 0
13 while(i>=0 || j>=0)
14 {
15 var sum:Int = carry
16 if i>=0
17 {
18 //获取该索引的字符
19 var char:Character = a[a.index(a.startIndex, offsetBy: i)]
20 //将字符转换成整数
21 for code in char.unicodeScalars {
22 //字符 0 的ASCII码为48
23 sum += (Int(code.value) - 48)
24 }
25 //自减
26 i-=1
27 }
28 if j>=0
29 {
30 //获取该索引的字符
31 var char:Character = b[b.index(b.startIndex, offsetBy: j)]
32 //将字符转换成整数
33 for code in char.unicodeScalars {
34 //字符 0 的ASCII码为48
35 sum += (Int(code.value) - 48)
36 }
37 //自减
38 j-=1
39 }
40 //转换为临时字符串
41 var temp = String(sum % 2)
42 //追加到字符串末尾
43 str.append(temp[temp.startIndex])
44 carry = sum/2
45 }
46 if carry != 0
47 {
48 //转换为临时字符串
49 var temp = String(carry)
50 //追加到字符串末尾
51 str.append(temp[temp.startIndex])
52 }
53 //返回逆序字符串
54 return String(str.reversed())
55 }
56 }40ms
1 class Solution {
2 func addBinary(_ a: String, _ b: String) -> String {
3 var arr1 = [Int]()
4 for c in a {
5 arr1.append(Int(String.init(c))!)
6 }
7 var arr2 = [Int]()
8 for c in b.unicodeScalars {
9 arr2.append(Int(String.init(c))!)
10 }
11 if arr1.count > arr2.count {
12 return addBinaryWithArr(arr1, short: arr2)
13 }
14 return addBinaryWithArr(arr2, short: arr1)
15 }
16
17 func addBinaryWithArr(_ long:[Int], short:[Int]) -> String {
18
19 func toString(_ array:[Int]) -> String {
20 var str = ""
21 for num in array {
22 str += "\(num)"
23 }
24 return str
25 }
26
27 var long = long
28 var target = 0
29 var initIndex = long.count - short.count
30 var i = short.count-1
31 while i >= 0 {
32 let temp = long[initIndex + i] + short[i] + target
33 if temp > 1 {
34 /// 有进位
35 long[initIndex + i] = temp - 2
36 target = 1
37 }else{
38 /// 无进位
39 long[initIndex + i] = temp
40 target = 0
41 }
42 i -= 1
43 }
44
45 if target == 0 {
46 return toString(long)
47 }
48
49 var j = initIndex - 1
50 while j >= 0 {
51 if long[j] == 0 {
52 long[j] = 1
53 return toString(long)
54 }
55 long[j] -= 1
56 j -= 1
57 }
58 return "1" + toString(long)
59 }
60 }48ms
1 class Solution {
2 func addBinary(_ a: String, _ b: String) -> String {
3
4 let str = String((a.count > b.count ? a: b).reversed())
5 let otherStr = String((a.count > b.count ? b: a).reversed())
6
7 var needUp = false
8 var result = ""
9
10 for i in 0..<str.count {
11
12 let index = str.index(String.Index(encodedOffset: i), offsetBy: 0)
13
14 let chara = i < otherStr.count ? otherStr[otherStr.index(String.Index(encodedOffset: i), offsetBy: 0)] : "0"
15
16 if str[index] == chara && (str[index] == "1" || str[index] == "0") {
17 result.insert(needUp ? "1":"0", at: String.Index(encodedOffset: 0))
18 needUp = str[index] == "1"
19 } else {
20 result.insert(needUp ? "0":"1", at: String.Index(encodedOffset: 0))
21 }
22
23 if i == str.count - 1 && needUp {
24 result.insert("1", at: String.Index(encodedOffset: 0))
25 }
26 }
27 return result
28
29 }
30 }