Merge pull request #1782 from sonjh1217/main

[sonjh1217] WEEK 03 solutions

Author: sonjh1217

number-of-1-bits/sonjh1217.swift

@@ -0,0 +1,54 @@
+class Solution {
+    func hammingWeightDivide(_ n: Int) -> Int {
+        var count = 0
+        var dividedNumber = n
+        while dividedNumber > 0 {
+            let remainder = dividedNumber % 2
+            if remainder == 1 {
+                count += 1
+            }
+            dividedNumber /= 2
+        }
+        
+        return count
+        
+        //시간 복잡도(O(log n))
+        //공간 복잡도(O(1))
+    }
+    
+    func hammingWeightShift(_ n: Int) -> Int {
+        var count = 0
+        
+        var shiftedNumber = n
+        while shiftedNumber > 0 {
+            if (shiftedNumber & 1) == 1 {
+                count += 1
+            }
+            shiftedNumber >>= 1
+        }
+        
+        return count
+        
+        //시간 복잡도(O(log n))
+        //공간 복잡도(O(1))
+    }
+    
+    func hammingWeightMask(_ n: Int) -> Int {
+        var count = 0
+        
+        var mask = 1 << 31
+        
+        while mask > 0 {
+            if mask & n == mask {
+                count += 1
+            }
+            mask >>= 1
+        }
+        
+        return count
+        
+        //시간 복잡도(O(1))
+        //공간 복잡도(O(1))
+    }
+}
+

valid-palindrome/sonjh1217.swift

@@ -0,0 +1,12 @@
+class Solution {
+    func isPalindrome(_ s: String) -> Bool {
+        let filtered = s.filter {$0.isLetter || $0.isWholeNumber}.lowercased()
+        let reversed = String(filtered.reversed())
+        
+        return filtered == reversed
+        
+        //시간 복잡도 O(n)
+        //공간 복잡도 O(n)
+    }
+}
+