Combination Sum

Given a set of candidate numbers (C) and a target number (T ), find all unique combinations in C where

the candidate numbers sums to T .

The same repeated number may be chosen from C unlimited number of times.

Note:

• All numbers (including target) will be positive integers.

• Elements in a combination (a1, a2, …, ak) must be in non-descending order. (ie, a1 > a2 > … > ak).

• The solution set must not contain duplicate combinations.

For example, given candidate set 2,3,6,7 and target 7, A solution set is:

[7]

[2, 2, 3]