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			24 lines
		
	
	
		
			561 B
		
	
	
	
		
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			24 lines
		
	
	
		
			561 B
		
	
	
	
		
			HTML
		
	
	
	
	
	
<p>Given an integer <code>n</code>, count <em>the total number of digit </em><code>1</code><em> appearing in all non-negative integers less than or equal to</em> <code>n</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> n = 13
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<strong>Output:</strong> 6
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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> n = 0
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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 <= n <= 10<sup>9</sup></code></li>
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</ul>
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