combination sum@leetcode

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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, � , a_k) must be in non-descending order. (ie, a₁ ? a₂ ? � ? a_k).
• 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] 

» Solve this problem

思路还是dynamic programming,用recursion做。和前面已经做过的一道题思路很像，只需要改一些细节，要注意这个元素本身可以重复使用，所以不需要设VISITED[]，但是很可能会出现重复的COMBINATION，所以要先SORT ARRAY。