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51 lines
1.7 KiB
HTML
51 lines
1.7 KiB
HTML
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<p>给你两个正整数 <code>n</code> 和 <code>k</code>。</p>
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<p>你可以选择 <code>n</code> 的 <strong>二进制表示</strong> 中任意一个值为 1 的位，并将其改为 0。</p>
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<p>返回使得 <code>n</code> 等于 <code>k</code> 所需要的更改次数。如果无法实现，返回 -1。</p>
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<p> </p>
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<p><strong class="example">示例 1：</strong></p>
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<div class="example-block">
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<p><strong>输入：</strong> <span class="example-io">n = 13, k = 4</span></p>
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<p><strong>输出：</strong> <span class="example-io">2</span></p>
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<p><strong>解释：</strong><br />
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最初，<code>n</code> 和 <code>k</code> 的二进制表示分别为 <code>n = (1101)<sub>2</sub></code> 和 <code>k = (0100)<sub>2</sub></code>，</p>
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<p>我们可以改变 <code>n</code> 的第一位和第四位。结果整数为 <code>n = (<u><strong>0</strong></u>10<u><strong>0</strong></u>)<sub>2</sub> = k</code>。</p>
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</div>
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<p><strong class="example">示例 2：</strong></p>
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<div class="example-block">
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<p><strong>输入：</strong> <span class="example-io">n = 21, k = 21</span></p>
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<p><strong>输出：</strong> <span class="example-io">0</span></p>
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<p><strong>解释：</strong><br />
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<code>n</code> 和 <code>k</code> 已经相等，因此不需要更改。</p>
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</div>
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<p><strong class="example">示例 3：</strong></p>
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<div class="example-block">
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<p><strong>输入：</strong> <span class="example-io">n = 14, k = 13</span></p>
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<p><strong>输出：</strong> <span class="example-io">-1</span></p>
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<p><strong>解释：</strong><br />
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无法使 <code>n</code> 等于 <code>k</code>。</p>
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</div>
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<p> </p>
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<p><strong>提示：</strong></p>
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<ul>
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<li><code>1 <= n, k <= 10<sup>6</sup></code></li>
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</ul>
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