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21 lines
706 B
HTML
21 lines
706 B
HTML
<p>Given a string <code>s</code>, <em>find the first non-repeating character in it and return its index</em>. If it does not exist, return <code>-1</code>.</p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<pre><strong>Input:</strong> s = "leetcode"
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<strong>Output:</strong> 0
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</pre><p><strong>Example 2:</strong></p>
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<pre><strong>Input:</strong> s = "loveleetcode"
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<strong>Output:</strong> 2
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</pre><p><strong>Example 3:</strong></p>
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<pre><strong>Input:</strong> s = "aabb"
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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><code>1 <= s.length <= 10<sup>5</sup></code></li>
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<li><code>s</code> consists of only lowercase English letters.</li>
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</ul>
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