Tag
Array\Backtracking
Difficulty
Medium
Description
Given a set of candidate numbers (C) (without duplicates) 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.
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]
]
Code
回溯

class Solution(object):
    def __init__(self):
        self.ret =[]

    def dfs(self,candidates,targets,tmplist):
        if sum(tmplist)==targets:
            self.ret.append(tmplist[:])
        elif sum(tmplist)>targets:
            pass
        else:
            for i in range(len(candidates)):
                tmplist.append(candidates[i])
                self.dfs(candidates[i:],targets,tmplist)
                tmplist.remove(tmplist[-1])
            #self.dfs(candidates,targets,tmplist)

    def combinationSum(self,candidates,targets):
        '''
        :param candidates: List[int]
        :param targets: int
        :return: List[List[int]]
        '''
        candidates.sort()
        self.dfs(candidates,targets,[])
        return self.ret