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			28 lines
		
	
	
		
			851 B
		
	
	
	
		
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			28 lines
		
	
	
		
			851 B
		
	
	
	
		
			HTML
		
	
	
	
	
	
<p>Given an unsorted array of integers <code>nums</code>, return <em>the length of the longest consecutive elements sequence.</em></p>
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<p>You must write an algorithm that runs in <code>O(n)</code> time.</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> nums = [100,4,200,1,3,2]
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<strong>Output:</strong> 4
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<strong>Explanation:</strong> The longest consecutive elements sequence is <code>[1, 2, 3, 4]</code>. Therefore its length is 4.
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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> nums = [0,3,7,2,5,8,4,6,0,1]
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<strong>Output:</strong> 9
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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 <= nums.length <= 10<sup>5</sup></code></li>
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	<li><code>-10<sup>9</sup> <= nums[i] <= 10<sup>9</sup></code></li>
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</ul>
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