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29 lines
1.4 KiB
HTML
29 lines
1.4 KiB
HTML
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<p>Implement <a href="http://www.cplusplus.com/reference/cstring/strstr/" target="_blank">strStr()</a>.</p>
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<p>Return the index of the first occurrence of needle in haystack, or <code>-1</code> if <code>needle</code> is not part of <code>haystack</code>.</p>
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<p><strong>Clarification:</strong></p>
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<p>What should we return when <code>needle</code> is an empty string? This is a great question to ask during an interview.</p>
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<p>For the purpose of this problem, we will return 0 when <code>needle</code> is an empty string. This is consistent to C's <a href="http://www.cplusplus.com/reference/cstring/strstr/" target="_blank">strstr()</a> and Java's <a href="https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(java.lang.String)" target="_blank">indexOf()</a>.</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> haystack = "hello", needle = "ll"
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<strong>Output:</strong> 2
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</pre><p><strong>Example 2:</strong></p>
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<pre><strong>Input:</strong> haystack = "aaaaa", needle = "bba"
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<strong>Output:</strong> -1
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</pre><p><strong>Example 3:</strong></p>
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<pre><strong>Input:</strong> haystack = "", needle = ""
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<strong>Output:</strong> 0
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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>0 <= haystack.length, needle.length <= 5 * 10<sup>4</sup></code></li>
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<li><code>haystack</code> and <code>needle</code> consist of only lower-case English characters.</li>
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</ul>
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