Leetcode (Python): Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

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 10,1,2,7,6,1,5 and target 8, 
A solution set is: 
[1, 7] 
[1, 2, 5] 
[2, 6] 
[1, 1, 6] 

Solution

class Solution:
    # @param candidates, a list of integers
    # @param target, integer
    # @return a list of lists of integers
    def combinationSum2(self, candidates, target):
        candidates.sort()
        solution =[]
        self.combinationSum2Rec(candidates, target, 0, 0, [], solution)
        return solution
    
    def combinationSum2Rec(self, candidates, target, index, sum, tempList, solution):
        if sum == target:
            solution.append(list(tempList))
            return
        for i in range(index, len(candidates)):
            if (i==index or candidates[i-1]!=candidates[i]) and sum+candidates[i]<=target:
                tempList.append(candidates[i])
                self.combinationSum2Rec(candidates, target, i+1, sum+candidates[i], tempList, solution) 
                tempList.pop()