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32 lines
1.3 KiB
HTML
32 lines
1.3 KiB
HTML
<p>Given the <code>head</code> of a singly linked list, group all the nodes with odd indices together followed by the nodes with even indices, and return <em>the reordered list</em>.</p>
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<p>The <strong>first</strong> node is considered <strong>odd</strong>, and the <strong>second</strong> node is <strong>even</strong>, and so on.</p>
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<p>Note that the relative order inside both the even and odd groups should remain as it was in the input.</p>
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<p>You must solve the problem in <code>O(1)</code> extra space complexity and <code>O(n)</code> time complexity.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2021/03/10/oddeven-linked-list.jpg" style="width: 300px; height: 123px;" />
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<pre>
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<strong>Input:</strong> head = [1,2,3,4,5]
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<strong>Output:</strong> [1,3,5,2,4]
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</pre>
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<p><strong>Example 2:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2021/03/10/oddeven2-linked-list.jpg" style="width: 500px; height: 142px;" />
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<pre>
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<strong>Input:</strong> head = [2,1,3,5,6,4,7]
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<strong>Output:</strong> [2,3,6,7,1,5,4]
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>n == </code>number of nodes in the linked list</li>
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<li><code>0 <= n <= 10<sup>4</sup></code></li>
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<li><code>-10<sup>6</sup> <= Node.val <= 10<sup>6</sup></code></li>
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</ul>
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