[LeetCode Sync] Runtime - 0 ms (100.00%), Memory - 17.7 MB (51.14%)

Author: NinePiece2

Solutions/0191-number-of-1-bits/README.md

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+<p>Given a positive integer <code>n</code>, write a function that returns the number of <span data-keyword="set-bit">set bits</span> in its binary representation (also known as the <a href="http://en.wikipedia.org/wiki/Hamming_weight" target="_blank">Hamming weight</a>).</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">n = 11</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">3</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p>The input binary string <strong>1011</strong> has a total of three set bits.</p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">n = 128</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">1</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p>The input binary string <strong>10000000</strong> has a total of one set bit.</p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">n = 2147483645</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">30</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p>The input binary string <strong>1111111111111111111111111111101</strong> has a total of thirty set bits.</p>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= n &lt;= 2<sup>31</sup> - 1</code></li>
+</ul>
+
+<p>&nbsp;</p>
+<strong>Follow up:</strong> If this function is called many times, how would you optimize it?

Solutions/0191-number-of-1-bits/solution.py

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+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        result = 0
+        while n:
+            n -= n & -n
+            result += 1
+        return result