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57 lines
1.5 KiB
HTML
57 lines
1.5 KiB
HTML
<p>给你一个整数数组 <code>arr</code> 。</p>
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<p>现需要从数组中取三个下标 <code>i</code>、<code>j</code> 和 <code>k</code> ，其中 <code>(0 <= i < j <= k < arr.length)</code> 。</p>
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<p><code>a</code> 和 <code>b</code> 定义如下：</p>
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<ul>
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<li><code>a = arr[i] ^ arr[i + 1] ^ ... ^ arr[j - 1]</code></li>
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<li><code>b = arr[j] ^ arr[j + 1] ^ ... ^ arr[k]</code></li>
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</ul>
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<p>注意：<strong>^</strong> 表示 <strong>按位异或</strong> 操作。</p>
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<p>请返回能够令 <code>a == b</code> 成立的三元组 (<code>i</code>, <code>j</code> , <code>k</code>) 的数目。</p>
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<p> </p>
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<p><strong>示例 1：</strong></p>
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<pre><strong>输入：</strong>arr = [2,3,1,6,7]
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<strong>输出：</strong>4
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<strong>解释：</strong>满足题意的三元组分别是 (0,1,2), (0,2,2), (2,3,4) 以及 (2,4,4)
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</pre>
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<p><strong>示例 2：</strong></p>
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<pre><strong>输入：</strong>arr = [1,1,1,1,1]
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<strong>输出：</strong>10
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</pre>
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<p><strong>示例 3：</strong></p>
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<pre><strong>输入：</strong>arr = [2,3]
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<strong>输出：</strong>0
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</pre>
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<p><strong>示例 4：</strong></p>
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<pre><strong>输入：</strong>arr = [1,3,5,7,9]
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<strong>输出：</strong>3
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</pre>
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<p><strong>示例 5：</strong></p>
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<pre><strong>输入：</strong>arr = [7,11,12,9,5,2,7,17,22]
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<strong>输出：</strong>8
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</pre>
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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 <= arr.length <= 300</code></li>
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<li><code>1 <= arr[i] <= 10^8</code></li>
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</ul>
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