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31 lines
2.2 KiB
HTML
31 lines
2.2 KiB
HTML
<p>You are given a string <code>s</code> and a character <code>c</code>. Return <em>the total number of <span data-keyword="substring-nonempty">substrings</span> of </em><code>s</code><em> that start and end with </em><code>c</code><em>.</em></p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
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<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "abada", c = "a"</span></p>
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<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">6</span></p>
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<p><strong>Explanation:</strong> Substrings starting and ending with <code>"a"</code> are: <code>"<strong><u>a</u></strong>bada"</code>, <code>"<u><strong>aba</strong></u>da"</code>, <code>"<u><strong>abada</strong></u>"</code>, <code>"ab<u><strong>a</strong></u>da"</code>, <code>"ab<u><strong>ada</strong></u>"</code>, <code>"abad<u><strong>a</strong></u>"</code>.</p>
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</div>
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<p><strong class="example">Example 2:</strong></p>
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<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
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<p><strong>Input: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "zzz", c = "z"</span></p>
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<p><strong>Output: </strong><span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">6</span></p>
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<p><strong>Explanation:</strong> There are a total of <code>6</code> substrings in <code>s</code> and all start and end with <code>"z"</code>.</p>
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</div>
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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> and <code>c</code> consist only of lowercase English letters.</li>
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</ul>
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