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			40 lines
		
	
	
		
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			40 lines
		
	
	
		
			1.6 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
<p>Given an encoded string, return its decoded string.</p>
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<p>The encoding rule is: <code>k[encoded_string]</code>, where the <code>encoded_string</code> inside the square brackets is being repeated exactly <code>k</code> times. Note that <code>k</code> is guaranteed to be a positive integer.</p>
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<p>You may assume that the input string is always valid; there are no extra white spaces, square brackets are well-formed, etc. Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, <code>k</code>. For example, there will not be input like <code>3a</code> or <code>2[4]</code>.</p>
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<p>The test cases are generated so that the length of the output will never exceed <code>10<sup>5</sup></code>.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> s = "3[a]2[bc]"
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<strong>Output:</strong> "aaabcbc"
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> s = "3[a2[c]]"
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<strong>Output:</strong> "accaccacc"
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</pre>
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<p><strong class="example">Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> s = "2[abc]3[cd]ef"
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<strong>Output:</strong> "abcabccdcdcdef"
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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 <= 30</code></li>
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	<li><code>s</code> consists of lowercase English letters, digits, and square brackets <code>'[]'</code>.</li>
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	<li><code>s</code> is guaranteed to be <strong>a valid</strong> input.</li>
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	<li>All the integers in <code>s</code> are in the range <code>[1, 300]</code>.</li>
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</ul>
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