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feat: add solutions to lc problem: No.0040
No.0040.Combination Sum II
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‎solution/0000-0099/0040.Combination Sum II/README.md

+129-2
Original file line numberDiff line numberDiff line change
@@ -38,9 +38,17 @@
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  [5]
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]</pre>
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## 解法
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DFS 回溯法。需要先对 candidates 数组进行排序。
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去重技巧：
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```python
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if i > u and candidates[i] == candidates[i - 1]:
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continue
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```
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<!-- 这里可写通用的实现逻辑 -->
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<!-- tabs:start -->
@@ -50,15 +58,134 @@
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def combinationSum2(self, candidates: List[int], target: int) -> List[List[int]]:
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def dfs(u, s, t):
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if s > target:
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return
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if s == target:
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ans.append(t[:])
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return
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for i in range(u, len(candidates)):
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if i > u and candidates[i] == candidates[i - 1]:
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continue
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t.append(candidates[i])
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dfs(i + 1, s + candidates[i], t)
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t.pop()
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ans = []
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candidates.sort()
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dfs(0, 0, [])
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return ans
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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private List<List<Integer>> ans;
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private int[] candidates;
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private int target;
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public List<List<Integer>> combinationSum2(int[] candidates, int target) {
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ans = new ArrayList<>();
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Arrays.sort(candidates);
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this.target = target;
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this.candidates = candidates;
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dfs(0, 0, new ArrayList<>());
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return ans;
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}
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private void dfs(int u, int s, List<Integer> t) {
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if (s > target) {
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return;
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}
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if (s == target) {
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ans.add(new ArrayList<>(t));
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return;
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}
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for (int i = u; i < candidates.length; ++i) {
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if (i > u && candidates[i] == candidates[i - 1]) {
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continue;
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}
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t.add(candidates[i]);
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dfs(i + 1, s + candidates[i], t);
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t.remove(t.size() - 1);
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}
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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vector<int> candidates;
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vector<vector<int>> ans;
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vector<int> t;
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int target;
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vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
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sort(candidates.begin(), candidates.end());
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this->candidates = candidates;
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this->target = target;
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vector<int> t;
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dfs(0, 0, t);
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return ans;
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}
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void dfs(int u, int s, vector<int>& t) {
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if (s > target) return;
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if (s == target)
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{
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ans.push_back(t);
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return;
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}
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for (int i = u; i < candidates.size(); ++i)
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{
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if (i > u && candidates[i] == candidates[i - 1]) continue;
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t.push_back(candidates[i]);
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dfs(i + 1, s + candidates[i], t);
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t.pop_back();
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}
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}
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};
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```
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### **Go**
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```go
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func combinationSum2(candidates []int, target int) [][]int {
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var ans [][]int
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var t []int
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sort.Ints(candidates)
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var dfs func(u, s int, t []int)
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dfs = func(u, s int, t []int) {
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if s > target {
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return
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}
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if s == target {
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cp := make([]int, len(t))
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copy(cp, t)
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ans = append(ans, cp)
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return
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}
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for i := u; i < len(candidates); i++ {
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if i > u && candidates[i] == candidates[i-1] {
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continue
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}
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t = append(t, candidates[i])
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dfs(i+1, s+candidates[i], t)
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t = t[:len(t)-1]
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}
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}
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dfs(0, 0, t)
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return ans
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}
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```
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### **...**

‎solution/0000-0099/0040.Combination Sum II/README_EN.md

+122-2
Original file line numberDiff line numberDiff line change
@@ -44,21 +44,141 @@
4444
<li><code>1 &lt;= target &lt;= 30</code></li>
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</ul>
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## Solutions
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DFS.
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5051
<!-- tabs:start -->
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5253
### **Python3**
5354

5455
```python
55-
56+
class Solution:
57+
def combinationSum2(self, candidates: List[int], target: int) -> List[List[int]]:
58+
def dfs(u, s, t):
59+
if s > target:
60+
return
61+
if s == target:
62+
ans.append(t[:])
63+
return
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for i in range(u, len(candidates)):
65+
if i > u and candidates[i] == candidates[i - 1]:
66+
continue
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t.append(candidates[i])
68+
dfs(i + 1, s + candidates[i], t)
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t.pop()
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ans = []
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candidates.sort()
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dfs(0, 0, [])
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return ans
5675
```
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5877
### **Java**
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6079
```java
80+
class Solution {
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private List<List<Integer>> ans;
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private int[] candidates;
83+
private int target;
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public List<List<Integer>> combinationSum2(int[] candidates, int target) {
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ans = new ArrayList<>();
87+
Arrays.sort(candidates);
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this.target = target;
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this.candidates = candidates;
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dfs(0, 0, new ArrayList<>());
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return ans;
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}
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private void dfs(int u, int s, List<Integer> t) {
95+
if (s > target) {
96+
return;
97+
}
98+
if (s == target) {
99+
ans.add(new ArrayList<>(t));
100+
return;
101+
}
102+
for (int i = u; i < candidates.length; ++i) {
103+
if (i > u && candidates[i] == candidates[i - 1]) {
104+
continue;
105+
}
106+
t.add(candidates[i]);
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dfs(i + 1, s + candidates[i], t);
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t.remove(t.size() - 1);
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}
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}
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}
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```
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### **C++**
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```cpp
117+
class Solution {
118+
public:
119+
vector<int> candidates;
120+
vector<vector<int>> ans;
121+
vector<int> t;
122+
int target;
123+
124+
vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
125+
sort(candidates.begin(), candidates.end());
126+
this->candidates = candidates;
127+
this->target = target;
128+
vector<int> t;
129+
dfs(0, 0, t);
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return ans;
131+
}
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133+
void dfs(int u, int s, vector<int>& t) {
134+
if (s > target) return;
135+
if (s == target)
136+
{
137+
ans.push_back(t);
138+
return;
139+
}
140+
for (int i = u; i < candidates.size(); ++i)
141+
{
142+
if (i > u && candidates[i] == candidates[i - 1]) continue;
143+
t.push_back(candidates[i]);
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dfs(i + 1, s + candidates[i], t);
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t.pop_back();
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}
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}
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};
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```
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### **Go**
152+
153+
```go
154+
func combinationSum2(candidates []int, target int) [][]int {
155+
var ans [][]int
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var t []int
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sort.Ints(candidates)
158+
var dfs func(u, s int, t []int)
159+
dfs = func(u, s int, t []int) {
160+
if s > target {
161+
return
162+
}
163+
if s == target {
164+
cp := make([]int, len(t))
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copy(cp, t)
166+
ans = append(ans, cp)
167+
return
168+
}
169+
for i := u; i < len(candidates); i++ {
170+
if i > u && candidates[i] == candidates[i-1] {
171+
continue
172+
}
173+
t = append(t, candidates[i])
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dfs(i+1, s+candidates[i], t)
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t = t[:len(t)-1]
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}
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}
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dfs(0, 0, t)
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return ans
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}
62182
```
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### **...**

‎solution/0000-0099/0040.Combination Sum II/Solution.cpp

+24-19
Original file line numberDiff line numberDiff line change
@@ -1,27 +1,32 @@
11
class Solution {
22
public:
3+
vector<int> candidates;
4+
vector<vector<int>> ans;
5+
vector<int> t;
6+
int target;
7+
38
vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
4-
vector<vector<int>> ans;
5-
vector<int> tmp;
6-
sort(candidates.begin(),candidates.end());
7-
int len = candidates.size();
8-
9-
dfs(ans,tmp,candidates,target,len,0);
10-
9+
sort(candidates.begin(), candidates.end());
10+
this->candidates = candidates;
11+
this->target = target;
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vector<int> t;
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dfs(0, 0, t);
1114
return ans;
1215
}
13-
14-
void dfs(vector<vector<int>> &ans,vector<int> &tmp,vector<int> &nums,int target,int len,int index) {
15-
16-
if(target == 0){
17-
auto iter = find(ans.begin(),ans.end(),tmp);
18-
if(iter == ans.end())ans.push_back(tmp);
16+
17+
void dfs(int u, int s, vector<int>& t) {
18+
if (s > target) return;
19+
if (s == target)
20+
{
21+
ans.push_back(t);
22+
return;
23+
}
24+
for (int i = u; i < candidates.size(); ++i)
25+
{
26+
if (i > u && candidates[i] == candidates[i - 1]) continue;
27+
t.push_back(candidates[i]);
28+
dfs(i + 1, s + candidates[i], t);
29+
t.pop_back();
1930
}
20-
21-
for(int i = index;i<len && target >= nums[i];i++){
22-
tmp.push_back(nums[i]);
23-
dfs(ans,tmp,nums,target - nums[i],len,i+1);//注意i+1
24-
tmp.pop_back();
25-
}
2631
}
2732
};

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