52 lines
2.1 KiB
Markdown
52 lines
2.1 KiB
Markdown
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给你一个字符串 <code>s</code> ，请你判断它是否 <strong>有效</strong> 。
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<p>字符串 <code>s</code> <strong>有效</strong> 需要满足：假设开始有一个空字符串 <code>t = ""</code> ，你可以执行 <strong>任意次</strong> 下述操作将<strong> </strong><code>t</code><strong> 转换为 </strong><code>s</code> ：</p>
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<ul>
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<li>将字符串 <code>"abc"</code> 插入到 <code>t</code> 中的任意位置。形式上，<code>t</code> 变为 <code>t<sub>left</sub> + "abc" + t<sub>right</sub></code>，其中 <code>t == t<sub>left</sub> + t<sub>right</sub></code> 。注意，<code>t<sub>left</sub></code> 和 <code>t<sub>right</sub></code> 可能为 <strong>空</strong> 。</li>
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</ul>
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<p>如果字符串 <code>s</code> 有效，则返回 <code>true</code>；否则，返回 <code>false</code>。</p>
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<p> </p>
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<p><strong>示例 1：</strong></p>
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<pre>
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<strong>输入：</strong>s = "aabcbc"
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<strong>输出：</strong>true
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<strong>解释：</strong>
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"" -> "<strong>abc</strong>" -> "a<strong>abc</strong>bc"
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因此，"aabcbc" 有效。</pre>
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<p><strong>示例 2：</strong></p>
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<pre>
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<strong>输入：</strong>s = "abcabcababcc"
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<strong>输出：</strong>true
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<strong>解释：</strong>
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"" -> "<strong>abc</strong>" -> "abc<strong>abc</strong>" -> "abcabc<strong>abc</strong>" -> "abcabcab<strong>abc</strong>c"
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因此，"abcabcababcc" 有效。</pre>
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<p><strong>示例 3：</strong></p>
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<pre>
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<strong>输入：</strong>s = "abccba"
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<strong>输出：</strong>false
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<strong>解释：</strong>执行操作无法得到 "abccba" 。</pre>
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<p><strong>示例 4：</strong></p>
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<pre>
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<strong>输入：</strong>s = "cababc"
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<strong>输出：</strong>false
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<strong>解释：</strong>执行操作无法得到 "cababc" 。</pre>
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<p> </p>
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<p><strong>提示：</strong></p>
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<ul>
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<li><code>1 <= s.length <= 2 * 10<sup>4</sup></code></li>
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<li><code>s</code> 由字母 <code>'a'</code>、<code>'b'</code> 和 <code>'c'</code> 组成</li>
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</ul>
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<div><div>Related Topics</div><div><li>栈</li><li>字符串</li></div></div>\n<div><li>👍 46</li><li>👎 0</li></div>
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