Hamming distance.

Author: recherst

Easy/461.Hamming Distance.playground/Contents.swift

@@ -0,0 +1,92 @@
+/**
+ The Hamming distance between two integers is the number of positions at which the corresponding bits are different.
+
+ Given two integers x and y, return the Hamming distance between them.
+
+  
+
+ Example 1:
+ 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.
+ 
+ Example 2:
+ Input: x = 3, y = 1
+ Output: 1
+  
+
+ Constraints:
+ - 0 <= x, y <= 231 - 1
+ */
+class Solution {
+    func hammingDistance(_ x: Int, _ y: Int) -> Int {
+        if x == y { return 0 }
+        var i = 0
+        var j = 0
+        while pow(2, i) <= x {
+            i += 1
+        }
+        i -= 1
+        var r = decimalToBinary(x, maxBit: i)
+        
+        while pow(2, j) <= y {
+            j += 1
+        }
+        j -= 1
+        var t = decimalToBinary(y, maxBit: j)
+        r = r.reversed()
+        t = t.reversed()
+        if r.count < t.count {
+            let temp = r
+            r = t
+            t = temp
+        }
+        let delta = abs(r.count - t.count)
+        if delta > 0 {
+            for _ in 0..<delta {
+                t.insert(0, at: 0)
+            }
+        }
+        
+        var times = 0
+        for i in 0..<r.count {
+            let e1 = r[i]
+            let e2 = t[i]
+            if e1 != e2 {
+                times += 1
+            }
+        }
+        return times
+    }
+    
+    private func pow(_ base: Int, _ power: Int) -> Int {
+        if base == 0 { return 0 }
+        var res = 1
+        for _ in 0..<power {
+            res *= base
+        }
+        return res
+    }
+    
+    private func decimalToBinary(_ num: Int, maxBit bit: Int) -> [Int] {
+        var n = num
+        var i = bit
+        var arr = Array(repeating: 0, count: bit + 1)
+        while i >= 0 && n > 0 {
+            while pow(2, i) <= n {
+                n -= pow(2, i)
+                arr[i] = 1
+            }
+            i -= 1
+        }
+        return arr
+    }
+}
+
+let s = Solution()
+let r = s.hammingDistance(333, 654)
+print(r)

Easy/461.Hamming Distance.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/461.Hamming Distance.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -93,6 +93,7 @@
 89. [Minimum Moves to Equal Array Elements](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/448.Minimum%20Moves%20toEqual%20Array%20Elements.playground/Contents.swift)
 90. [Assign Cookies](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/455.Assign%20Cookies.playground/Contents.swift)
 91. [Repeated Substring Pattern](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/459.Repeated%20Substring%20Pattern.playground/Contents.swift)
+92. [Hamming Distance](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/461.Hamming%20Distance.playground/Contents.swift)
 
 #### Medium