Package g0201_0300.s0216_combination_sum_iii

Class Solution

java.lang.Object
g0201_0300.s0216_combination_sum_iii.Solution
public class Solution extends Object
216 - Combination Sum III.

Medium

Find all valid combinations of k numbers that sum up to n such that the following conditions are true:

  • Only numbers 1 through 9 are used.
  • Each number is used at most once.

Return a list of all possible valid combinations. The list must not contain the same combination twice, and the combinations may be returned in any order.

Example 1:

Input: k = 3, n = 7

Output: 1,2,4

Explanation:

 1 + 2 + 4 = 7
 There are no other valid combinations.

Example 2:

Input: k = 3, n = 9

Output: [[1,2,6],[1,3,5],[2,3,4]]

Explanation:

 1 + 2 + 6 = 9
 1 + 3 + 5 = 9
 2 + 3 + 4 = 9
 There are no other valid combinations.

Example 3:

Input: k = 4, n = 1

Output: []

Explanation:

 There are no valid combinations.
 Using 4 different numbers in the range [1,9], the smallest sum we can get is 1+2+3+4 = 10 and since 10 > 1, there are no valid combination.

Example 4:

Input: k = 3, n = 2

Output: []

Explanation: There are no valid combinations.

Example 5:

Input: k = 9, n = 45

Output: 1,2,3,4,5,6,7,8,9

Explanation:

 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45
 There are no other valid combinations.

Constraints:

  • 2 <= k <= 9
  • 1 <= n <= 60

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • combinationSum3

      public List<List<Integer>> combinationSum3(int k, int n)