combination_sum.py

class Solution:
    def helper(self, candidates, target, curr_comb, result, curr_id, curr_sum):
        if curr_sum >= target:
            if curr_sum == target:
                result.append(curr_comb)
            return
        
        for i in range(curr_id, len(candidates)):
            curr_comb.append(candidates[i])
            self.helper(candidates, target, curr_comb, result, i, curr_sum + candidates[i])
            curr_comb.pop()
        
    def combinationSum(self, candidates, target):
        """
        :type candidates: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        result = []
        self.helper(candidates, target, [], result, 0, 0)
        return result