Combinations

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Description

tab: English
 
<p>Given two integers <code>n</code> and <code>k</code>, return <em>all possible combinations of</em> <code>k</code> <em>numbers chosen from the range</em> <code>[1, n]</code>.</p>
 
<p>You may return the answer in <strong>any order</strong>.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
 
<pre>
<strong>Input:</strong> n = 4, k = 2
<strong>Output:</strong> [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
<strong>Explanation:</strong> There are 4 choose 2 = 6 total combinations.
Note that combinations are unordered, i.e., [1,2] and [2,1] are considered to be the same combination.
</pre>
 
<p><strong class="example">Example 2:</strong></p>
 
<pre>
<strong>Input:</strong> n = 1, k = 1
<strong>Output:</strong> [[1]]
<strong>Explanation:</strong> There is 1 choose 1 = 1 total combination.
</pre>
 
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li><code>1 &lt;= n &lt;= 20</code></li>
	<li><code>1 &lt;= k &lt;= n</code></li>
</ul>
 
 
 
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[submissions](https://leetcode.com/problems/combinations/submissions/) | [solutions](https://leetcode.com/problems/combinations/solutions/)
 
 
tab: 中文
 
<p>给定两个整数 <code>n</code> 和 <code>k</code>，返回范围 <code>[1, n]</code> 中所有可能的 <code>k</code> 个数的组合。</p>
 
<p>你可以按 <strong>任何顺序</strong> 返回答案。</p>
 
<p> </p>
 
<p><strong>示例 1：</strong></p>
 
<pre>
<strong>输入：</strong>n = 4, k = 2
<strong>输出：</strong>
[
  [2,4],
  [3,4],
  [2,3],
  [1,2],
  [1,3],
  [1,4],
]</pre>
 
<p><strong>示例 2：</strong></p>
 
<pre>
<strong>输入：</strong>n = 1, k = 1
<strong>输出：</strong>[[1]]</pre>
 
<p> </p>
 
<p><strong>提示：</strong></p>
 
<ul>
	<li><code>1 <= n <= 20</code></li>
	<li><code>1 <= k <= n</code></li>
</ul>
 
 
 
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[提交记录](https://leetcode.cn/problems/combinations/submissions/) | [题解](https://leetcode.cn/problems/combinations/solution/)
 
 

Solutions & Notes

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