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 (a1a2, … , 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
        


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