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 toT.
Each number in C may only be used once in the combination.
Note:
All numbers (including target) will be positive integers.
The solution set must not contain duplicate combinations.
For example, given candidate set[10, 1, 2, 7, 6, 1, 5]
and target8
,
A solution set is:
[
[1, 7],
[1, 2, 5],
[2, 6],
[1, 1, 6]
]
分析
注意这里 target == 0 加入res . 《0或者重复时候,不一样处理
class Solution:
def combinationSum2(self, c: List[int], target: int) -> List[List[int]]:
c.sort()
res = []
n=len(c)
def dfs(pos,path,target):
if target == 0:
res.append(path)
for i in range(pos,n ):
if c[i] > target:
return
if i!=pos and c[i]==c[i-1]:
continue #!!!!!!
dfs(i+1,path+[c[i]],target - c[i])
dfs(0,[],target)
return res
DSF带去重和带Pos:candidates[i - 1] == candidates[i] && !visited[i-1]
class Solution {
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
List<List<Integer>> ret = new ArrayList<>();
if(candidates == null || candidates.length == 0)
return ret;
List<Integer> path = new ArrayList<Integer>();
boolean[] visited = new boolean[candidates.length];
Arrays.sort(candidates);
dfs(candidates, path, ret, target, 0 , visited);
return ret;
}
public void dfs(int[] candidates, List<Integer> path, List<List<Integer>> ret, int sum, int pos, boolean[] visited){
if(sum < 0)
return;
if(sum == 0){
if(!ret.contains(path))
ret.add(new ArrayList<Integer>(path));
return;
}
for(int i = pos; i < candidates.length; i ++){
if(visited[i] || (i != 0 && candidates[i - 1] == candidates[i] && !visited[i-1])){
continue;
}else{
path.add(candidates[i]);
visited[i] = true;
dfs(candidates, path, ret, sum - candidates[i], i + 1,visited);
path.remove(path.size() - 1);
visited[i] = false;
}
}
}
}
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