Leetcode (Python): Combination Sum

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]

Solution:

class Solution:
    # @param candidates, a list of integers
    # @param target, integer
    # @return a list of lists of integers
    def combinationSum(self, candidates, target):
        candidates.sort()
        solution=[]
        self.combinationSumRec(candidates, target, 0, 0, [], solution)
        return solution
        
    def combinationSumRec(self, candidates, target, index, sum, listT, solution):
        if sum == target:
            solution.append(list(listT))
        for i in range(index,len(candidates)):
            if sum + candidates[i] > target:
                break;
            listT.append(candidates[i])
            self.combinationSumRec(candidates, target, i, sum+candidates[i], listT, solution)
            listT.pop()