combination-sum.py

"""
Combination Sum
https://leetcode.com/problems/combination-sum/

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]
]
"""


class Solution(object):
    def combinationSum(self, candidates, target):
        """
        :type candidates: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        result = []

        def dfs(candidates, target, path):
            if target < 0:
                return
            if target == 0:
                result.append(path)
            for i in range(len(candidates)):
                dfs(candidates[i:], target -
                    candidates[i], path + [candidates[i]])
        dfs(candidates, target, [])
        return result


t = [2, 3, 6, 7]
r = Solution().combinationSum(t, 7)
print(r)