LeetCode----Combination Sum II

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]

 

分析：

跟前面的题很相似，给定的candidates中有重复的数，并且每个数只能使用一次。在上一题的代码中稍作修改即可。

代码：

class Solution(object):
def combinationSum2(self, candidates, target):
"""
:type candidates: List[int]
:type target: int
:rtype: List[List[int]]
"""
solutions = []
candidates.sort()
self.dfs(candidates, target, 0, len(candidates) - 1, list(), solutions)
return solutions

def dfs(self, candidates, gap, start, end, knums, solutions):
if gap == 0:
if knums not in solutions:
solutions.append(knums)
return

i = start
while i <= end:
if gap < candidates[i]:
return
self.dfs(candidates, gap - candidates[i], i + 1, end, knums + [candidates[i]], solutions)
i += 1