40. Combination Sum II leetcode Python 2016 new season

hyperbolechi

于 2016-01-24 10:58:45 发布

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本文介绍了一种寻找候选数集合中所有唯一组合的算法，这些组合的和等于目标数。文章详细阐述了如何通过递归搜索的方法实现这一过程，并确保组合不重复且按非递减顺序排列。

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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]

class Solution(object):
    def bfs(self, candidates, target, result, valuelist, start):
        if target == 0 and valuelist not in result:
            return result.append(valuelist)
        for index in range(start, len(candidates)):
            if target < candidates[index]:
                return
            self.bfs(candidates, target - candidates[index], result, valuelist + [candidates[index]], index + 1)
    def combinationSum2(self, candidates, target):
        """
        :type candidates: List[int]
        :type target: int
        :rtype: List[List[int]]
        """
        candidates.sort()
        result = []
        self.bfs(candidates, target, result, [], 0)
        return result