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Combinations

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	`1`	`+'''Leetcode- https://leetcode.com/problems/combinations/'''`
	`2`	`+'''`
	`3`	`+Given two integers n and k, return all possible combinations of k numbers out of the range [1, n].`
	`4`	`+`
	`5`	`+You may return the answer in any order.`
	`6`	`+`
	`7`	`+Example 1:`
	`8`	`+`
	`9`	`+Input: n = 4, k = 2`
	`10`	`+Output:`
	`11`	`+[`
	`12`	`+ [2,4],`
	`13`	`+ [3,4],`
	`14`	`+ [2,3],`
	`15`	`+ [1,2],`
	`16`	`+ [1,3],`
	`17`	`+ [1,4],`
	`18`	`+]`
	`19`	`+'''`
	`20`	`+def combine(n, k):`
	`21`	`+ result = []`
	`22`	`+`
	`23`	`+ def backtrack(start,comb):`
	`24`	`+ if len(comb) == k:`
	`25`	`+ result.append(comb.copy())`
	`26`	`+ return`
	`27`	`+`
	`28`	`+ for i in range(start,n+1):`
	`29`	`+ comb.append(i)`
	`30`	`+ backtrack(i+1,comb)`
	`31`	`+ comb.pop()`
	`32`	`+`
	`33`	`+ backtrack(1,[])`
	`34`	`+ return result`
	`35`	`+`
	`36`	`+#T: O(k.n^k)`
	`37`	`+#T: O(k. n!/(n-k)!k!)`
	`38`	`+#S: O(n)`

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`@@ -12,4 +12,5 @@ Check the notes for the explaination - [Notes](https://stingy-shallot-4ea.notion`
`12`	`12`	`- [x] [Subsets-II](Backtracking/78-Subsets.py)`
`13`	`13`	`- [x] [Permutations](Backtracking/46-Permutations.py)`
`14`	`14`	`- [x] [Permutations II](Backtracking/47-Permutations-II.py)`
	`15`	`+ - [x] [Combinations](Backtracking/77-Combinations.py)`
`15`	`16`

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