39. Combination Sum leetcode python 2016 new season

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] 

class Solution(object):    def bfs(self, candidates, target, start, valuelist, result):        if target == 0:            return result.append(valuelist)        for index in range(start, len(candidates)):            if target < candidates[index]:                return            self.bfs(candidates, target - candidates[index], index, valuelist + [candidates[index]], result)    def combinationSum(self, candidates, target):        """        :type candidates: List[int]        :type target: int        :rtype: List[List[int]]        """        candidates.sort()        result = []        self.bfs(candidates, target, 0, [], result)        return result