[yayyz] WEEK 03 solutions

number-of-1-bits/yayyz.py

@@ -0,0 +1,12 @@
+# bit operation 
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        count = 0
+        while n:
+            count += n & 1
+            n >>= 1
+        return count 
+
+# class Solution:
+#     def hammingWeight(self, n: int) -> int:
+#         return bin(n).count('1')

valid-palindrome/yayyz.py

@@ -0,0 +1,15 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:        
+        s = ''.join(filter(str.isalnum, s)).lower()
+        if not (s and s.strip()): return True 
+
+        head = 0
+        tail = len(s) -1
+        while head < tail:
+            if s[head] != s[tail]:
+                return False
+            else: 
+                head += 1
+                tail -= 1
+
+        return True