[jongwanra] WEEK 03 solutions

number-of-1-bits/jongwanra.py

@@ -0,0 +1,45 @@
+"""
+[Problem]
+https://leetcode.com/problems/number-of-1-bits/description/
+
+양수 n이 주어졌을 때, 이진법에서 1로 설정된 비트의 개수를 반환하는 함수를 작성해라.
+
+
+[Plan]
+1. 주어진 양수를 이진수로 변환한다.
+2. for-loop을 순회하며 1의 개수를 counting한다.
+
+[Complexity]
+N: bin(n).length - 2
+Time: O(N)
+Space = O(N)
+"""
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        binary = bin(n)
+        output = 0
+        for index in range(2, len(binary)):
+            if binary[index] == '1':
+                output += 1
+        return output
+"""
+ref: https://www.algodale.com/problems/number-of-1-bits/
+[Complexity]
+Time: O(log n)
+Space: O(1)
+"""
+class AnotherSolution:
+    def hammingWeight(self, n: int) -> int:
+        count = 0
+        while n:
+            quotient, remainder = divmod(n, 2)
+            print(f"n = {n} quotient={quotient}, remainder={remainder}")
+            count += remainder
+            n = quotient
+        return count
+
+sol = AnotherSolution()
+print(sol.hammingWeight(11) == 3)
+print(sol.hammingWeight(128) == 1)
+print(sol.hammingWeight(2147483645) == 30)
+