Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers.
Note:
All numbers will be positive integers.
The solution set must not contain duplicate combinations.
Example 1:
1 2
Input: k = 3, n = 7 Output: [[1,2,4]]
Example 2:
1 2
Input: k = 3, n = 9 Output: [[1,2,6], [1,3,5], [2,3,4]]
class : defcombinationSum3(self, k: int, n: int) -> 'list[list[int]]': defdfs(current, sum): if len(current) == k and sum == n: result.append(copy.deepcopy(current)) return
if sum >= n or len(current) >= k: return
start = 1if len(current) == 0else current[-1] + 1 for i in range(start, 10, 1): sum += i current.append(i) dfs(current, sum) sum -= i current.pop()
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