[Swift]LeetCode461. 漢明距離 | Hamming Distance

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The Hamming distance between two integers is the number of positions at which the corresponding bits are different.

Given two integers x and y, calculate the Hamming distance.

Note:
0 ≤ x, y < 231.

Example:

Input: x = 1, y = 4

Output: 2

Explanation:
1   (0 0 0 1)
4   (0 1 0 0)
       ↑   ↑

The above arrows point to positions where the corresponding bits are different.

---

兩個整數之間的漢明距離指的是這兩個數字對應二進制位不一樣的位置的數目。

給出兩個整數 x 和 y，計算它們之間的漢明距離。

注意：
0 ≤ x, y < 231.

示例:

輸入: x = 1, y = 4

輸出: 2

解釋:
1   (0 0 0 1)
4   (0 1 0 0)
       ↑   ↑

上面的箭頭指出了對應二進制位不一樣的位置。

---

8ms

1 class Solution {
2     func hammingDistance(_ x: Int, _ y: Int) -> Int {
3         return (x^y).nonzeroBitCount
4     }
5 }

---

8ms

1 class Solution {
2     func hammingDistance(_ x: Int, _ y: Int) -> Int {
3         if (x ^ y) == 0 {return 0}
4         return (x ^ y) % 2 + hammingDistance(x / 2, y / 2)
5     }
6 }

---

8ms

1 class Solution {
2     func hammingDistance(_ x: Int, _ y: Int) -> Int {
3         return String(x ^ y, radix: 2).replacingOccurrences(of: "0", with: "").count
4     }
5 }

---

8ms

 1 class Solution {
 2     func hammingDistance(_ x: Int, _ y: Int) -> Int {
 3         var r = x ^ y
 4         // 這個就是計算位數爲1的方法
 5         var count = 0
 6         while r != 0 {
 7             r = r & (r - 1)
 8             count += 1
 9         }
10         return count
11     }
12 }

---

12ms

 1 class Solution {
 2 func hammingDistance(_ x: Int, _ y: Int) -> Int {
 3     var numX = min(x, y)
 4     var numY = max(x, y)
 5     var result = 0
 6     while numY > 0 {
 7         if (numX % 2 != numY % 2) {
 8             result += 1
 9         }
10         numX = numX / 2
11         numY = numY / 2
12     }
13     return result
14   }
15 }

---

12ms

 1 class Solution {
 2     func pad(string : String, toSize: Int) -> String {
 3     var padded = string
 4     for _ in 0..<(toSize - string.characters.count) {
 5         padded = "0" + padded
 6     }
 7     return padded
 8 }
 9     
10     func hammingDistance(_ x: Int, _ y: Int) -> Int {
11             guard x >= 0 && y < 4294967296 else {
12         return 0
13     }
14     var a = pad(string: String(x, radix: 2, uppercase: false), toSize: 32)
15     var b = pad(string: String(y, radix: 2, uppercase: false), toSize: 32)
16     var res = 0
17     for i in 0..<32 {
18         if a[a.index(a.startIndex, offsetBy: i)] != b[b.index(b.startIndex, offsetBy: i)] {
19             res += 1
20         }
21     }
22     return res
23     }
24 }