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