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32 lines
903 B
HTML
32 lines
903 B
HTML
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<p>Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.)</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/2020/10/03/swap_ex1.jpg" style="width: 422px; height: 222px;" />
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<pre>
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<strong>Input:</strong> head = [1,2,3,4]
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<strong>Output:</strong> [2,1,4,3]
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> head = []
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<strong>Output:</strong> []
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</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> head = [1]
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<strong>Output:</strong> [1]
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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>The number of nodes in the list is in the range <code>[0, 100]</code>.</li>
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<li><code>0 <= Node.val <= 100</code></li>
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</ul>
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