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Commit 81d9fdd

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feat: update solutions to lc/lcof2 problems
lc No.0187.Repeated DNA Sequences lc No.0206, lcof2 No.024.Reverse Linked List
1 parent 13e2cef commit 81d9fdd

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16 files changed

+480
-219
lines changed

16 files changed

+480
-219
lines changed

‎lcof2/剑指 Offer II 024. 反转链表/README.md‎

Lines changed: 89 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -50,10 +50,13 @@
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<p><meta charset="UTF-8" />注意:本题与主站 206&nbsp;题相同:&nbsp;<a href="https://leetcode-cn.com/problems/reverse-linked-list/">https://leetcode-cn.com/problems/reverse-linked-list/</a></p>
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53-
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## 解法
5554

56-
<!-- 这里可写通用的实现逻辑 -->
55+
定义指针 `p`、`q` 分别指向头节点和下一个节点,`pre` 指向头节点的前一个节点。
56+
57+
遍历链表,改变指针 `p` 指向的节点的指向,将其指向 `pre` 指针指向的节点,即 `p.next = pre`。然后 `pre` 指针指向 `p`,`p`、`q` 指针往前走。
58+
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当遍历结束后,返回 `pre` 指针即可。
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<!-- tabs:start -->
5962

@@ -133,44 +136,105 @@ class Solution {
133136
```js
134137
/**
135138
* Definition for singly-linked list.
136-
* function ListNode(val) {
137-
* this.val = val;
138-
* this.next = null;
139+
* function ListNode(val, next) {
140+
* this.val = (val===undefined ? 0 : val)
141+
* this.next = (next===undefined ? null : next)
139142
* }
140143
*/
141144
/**
142145
* @param {ListNode} head
143146
* @return {ListNode}
144147
*/
145-
var reverseList = function (head) {
146-
let node = head;
147-
let pre = null;
148-
while (node) {
149-
let cur = node;
150-
node = cur.next;
151-
cur.next = pre;
152-
pre = cur;
153-
}
154-
return pre;
148+
var reverseList = function(head) {
149+
let pre = null;
150+
for (let p = head; p;) {
151+
let q = p.next;
152+
p.next = pre;
153+
pre = p;
154+
p = q;
155+
}
156+
return pre;
155157
};
156158
```
157159

158160
### **Go**
159161

160162
```go
163+
/**
164+
* Definition for singly-linked list.
165+
* type ListNode struct {
166+
* Val int
167+
* Next *ListNode
168+
* }
169+
*/
161170
func reverseList(head *ListNode) *ListNode {
162-
if head == nil ||head.Next == nil {
163-
return head
171+
var pre *ListNode
172+
for p := head; p != nil; {
173+
q := p.Next
174+
p.Next = pre
175+
pre = p
176+
p = q
177+
}
178+
return pre
179+
}
180+
```
181+
182+
### **C++**
183+
184+
```cpp
185+
/**
186+
* Definition for singly-linked list.
187+
* struct ListNode {
188+
* int val;
189+
* ListNode *next;
190+
* ListNode() : val(0), next(nullptr) {}
191+
* ListNode(int x) : val(x), next(nullptr) {}
192+
* ListNode(int x, ListNode *next) : val(x), next(next) {}
193+
* };
194+
*/
195+
class Solution {
196+
public:
197+
ListNode* reverseList(ListNode* head) {
198+
ListNode* pre = nullptr;
199+
ListNode* p = head;
200+
while (p)
201+
{
202+
ListNode* q = p->next;
203+
p->next = pre;
204+
pre = p;
205+
p = q;
206+
}
207+
return pre;
164208
}
165-
dummyHead := &ListNode{}
166-
cur := head
167-
for cur != nil {
168-
tmp := cur.Next
169-
cur.Next = dummyHead.Next
170-
dummyHead.Next = cur
171-
cur = tmp
209+
};
210+
```
211+
212+
### **C#**
213+
214+
```cs
215+
/**
216+
* Definition for singly-linked list.
217+
* public class ListNode {
218+
* public int val;
219+
* public ListNode next;
220+
* public ListNode(int val=0, ListNode next=null) {
221+
* this.val = val;
222+
* this.next = next;
223+
* }
224+
* }
225+
*/
226+
public class Solution {
227+
public ListNode ReverseList(ListNode head) {
228+
ListNode pre = null;
229+
for (ListNode p = head; p != null;)
230+
{
231+
ListNode t = p.next;
232+
p.next = pre;
233+
pre = p;
234+
p = t;
235+
}
236+
return pre;
172237
}
173-
return dummyHead.Next
174238
}
175239
```
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
1+
/**
2+
* Definition for singly-linked list.
3+
* struct ListNode {
4+
* int val;
5+
* ListNode *next;
6+
* ListNode() : val(0), next(nullptr) {}
7+
* ListNode(int x) : val(x), next(nullptr) {}
8+
* ListNode(int x, ListNode *next) : val(x), next(next) {}
9+
* };
10+
*/
11+
class Solution {
12+
public:
13+
ListNode* reverseList(ListNode* head) {
14+
ListNode* pre = nullptr;
15+
ListNode* p = head;
16+
while (p)
17+
{
18+
ListNode* q = p->next;
19+
p->next = pre;
20+
pre = p;
21+
p = q;
22+
}
23+
return pre;
24+
}
25+
};
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Original file line numberDiff line numberDiff line change
@@ -1,13 +1,24 @@
1+
/**
2+
* Definition for singly-linked list.
3+
* public class ListNode {
4+
* public int val;
5+
* public ListNode next;
6+
* public ListNode(int val=0, ListNode next=null) {
7+
* this.val = val;
8+
* this.next = next;
9+
* }
10+
* }
11+
*/
112
public class Solution {
213
public ListNode ReverseList(ListNode head) {
3-
ListNode newHead = null;
4-
while(head!= null)
14+
ListNode pre = null;
15+
for(ListNodep=head;p!= null;)
516
{
6-
varnext = head.next;
7-
head.next = newHead;
8-
newHead = head;
9-
head = next;
17+
ListNodet = p.next;
18+
p.next = pre;
19+
pre = p;
20+
p = t;
1021
}
11-
return newHead;
22+
return pre;
1223
}
1324
}
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Original file line numberDiff line numberDiff line change
@@ -1,14 +1,17 @@
1+
/**
2+
* Definition for singly-linked list.
3+
* type ListNode struct {
4+
* Val int
5+
* Next *ListNode
6+
* }
7+
*/
18
func reverseList(head *ListNode) *ListNode {
2-
if head == nil ||head.Next == nil {
3-
return head
4-
}
5-
dummyHead := &ListNode{}
6-
cur := head
7-
for cur != nil {
8-
tmp := cur.Next
9-
cur.Next = dummyHead.Next
10-
dummyHead.Next = cur
11-
cur = tmp
12-
}
13-
return dummyHead.Next
9+
var pre *ListNode
10+
for p := head; p != nil; {
11+
q := p.Next
12+
p.Next = pre
13+
pre = p
14+
p = q
15+
}
16+
return pre
1417
}
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Original file line numberDiff line numberDiff line change
@@ -1,22 +1,21 @@
11
/**
22
* Definition for singly-linked list.
3-
* function ListNode(val) {
4-
* this.val = val;
5-
* this.next = null;
3+
* function ListNode(val, next) {
4+
* this.val = (val===undefined ? 0 : val)
5+
* this.next = (next===undefined ? null : next)
66
* }
77
*/
88
/**
99
* @param {ListNode} head
1010
* @return {ListNode}
1111
*/
12-
var reverseList = function (head) {
13-
let node = head;
14-
let pre = null;
15-
while (node) {
16-
let cur = node;
17-
node = cur.next;
18-
cur.next = pre;
19-
pre = cur;
20-
}
21-
return pre;
22-
};
12+
var reverseList = function(head) {
13+
let pre = null;
14+
for (let p = head; p;) {
15+
let q = p.next;
16+
p.next = pre;
17+
pre = p;
18+
p = q;
19+
}
20+
return pre;
21+
};

‎solution/0100-0199/0187.Repeated DNA Sequences/README.md‎

Lines changed: 27 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -49,15 +49,15 @@
4949
```python
5050
class Solution:
5151
def findRepeatedDnaSequences(self, s: str) -> List[str]:
52-
n = 10
53-
subs = set()
54-
res = set()
55-
for i in range(len(s) -n + 1):
56-
sub = s[i:i + n]
57-
ifsubin subs:
58-
res.add(sub)
59-
subs.add(sub)
60-
return list(res)
52+
n = len(s) -10
53+
cnt = collections.Counter()
54+
ans = []
55+
for i in range(n + 1):
56+
sub = s[i:i + 10]
57+
cnt[sub] +=1
58+
if cnt[sub] ==2:
59+
ans.append(sub)
60+
return ans
6161
```
6262

6363
### **Java**
@@ -67,17 +67,17 @@ class Solution:
6767
```java
6868
class Solution {
6969
public List<String> findRepeatedDnaSequences(String s) {
70-
int len = 10;
71-
Set<String> subs = new HashSet<>();
72-
Set<String> res = new HashSet<>();
73-
for (int i = 0; i < s.length() - len + 1; ++i) {
74-
String sub = s.substring(i, i + len);
75-
if (subs.contains(sub)) {
76-
res.add(sub);
70+
int n = s.length() - 10;
71+
Map<String, Integer> cnt = new HashMap<>();
72+
List<String> ans = new ArrayList<>();
73+
for (int i = 0; i <= n; ++i) {
74+
String sub = s.substring(i, i + 10);
75+
cnt.put(sub, cnt.getOrDefault(sub, 0) + 1);
76+
if (cnt.get(sub) == 2) {
77+
ans.add(sub);
7778
}
78-
subs.add(sub);
7979
}
80-
return newArrayList<>(res);
80+
return ans;
8181
}
8282
}
8383
```
@@ -90,17 +90,17 @@ class Solution {
9090
* @return {string[]}
9191
*/
9292
var findRepeatedDnaSequences = function(s) {
93-
let n = 10;
94-
let subs = new Set();
95-
let res = new Set();
96-
for (let i = 0; i < s.length - n + 1; i++) {
97-
let sub = s.slice(i, i + n);
98-
if (subs.has(sub)) {
99-
res.add(sub);
93+
const n = s.length - 10;
94+
let cnt = new Map();
95+
let ans = [];
96+
for (let i = 0; i <= n; ++i) {
97+
let sub = s.slice(i, i + 10);
98+
cnt[sub] = (cnt[sub] || 0) + 1;
99+
if (cnt[sub] == 2) {
100+
ans.push(sub);
100101
}
101-
subs.add(sub);
102102
}
103-
return [...res];
103+
return ans;
104104
};
105105
```
106106

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