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feat: add solutions to lcof2 problems: No.028,029
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6 files changed

+279
-4
lines changed

6 files changed

+279
-4
lines changed

Diff for: ‎lcof2/剑指 Offer II 028. 展平多级双向链表/README.md

+72-2
Original file line numberDiff line numberDiff line change
@@ -99,22 +99,92 @@
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<!-- 这里可写通用的实现逻辑 -->
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仔细观察一下这个结构，不难发现其实就是前序遍历二叉树
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<!-- tabs:start -->
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### **Python3**
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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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"""
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# Definition for a Node.
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class Node:
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def __init__(self, val, prev, next, child):
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self.val = val
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self.prev = prev
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self.next = next
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self.child = child
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"""
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class Solution:
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def flatten(self, head: 'Node') -> 'Node':
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if head is None:
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return None
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dummy = Node()
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tail = dummy
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def preOrder(node: 'Node'):
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nonlocal tail
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if node is None:
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return
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next = node.next
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child = node.child
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tail.next = node
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node.prev = tail
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tail = tail.next
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node.child = None
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preOrder(child)
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preOrder(next)
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preOrder(head)
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dummy.next.prev = None
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return dummy.next
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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
117-
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/*
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// Definition for a Node.
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class Node {
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public int val;
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public Node prev;
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public Node next;
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public Node child;
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};
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*/
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class Solution {
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private Node dummy = new Node();
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private Node tail = dummy;
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public Node flatten(Node head) {
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if (head == null) {
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return null;
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}
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preOrder(head);
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dummy.next.prev = null;
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return dummy.next;
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}
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private void preOrder(Node node) {
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if (node == null) {
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return;
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}
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Node next = node.next;
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Node child = node.child;
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tail.next = node;
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node.prev = tail;
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tail = tail.next;
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node.child = null;
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preOrder(child);
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preOrder(next);
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}
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}
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```
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### **...**

Diff for: ‎lcof2/剑指 Offer II 028. 展平多级双向链表/Solution.java

+37
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,37 @@
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/*
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// Definition for a Node.
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class Node {
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public int val;
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public Node prev;
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public Node next;
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public Node child;
8+
};
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*/
10+
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class Solution {
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private Node dummy = new Node();
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private Node tail = dummy;
14+
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public Node flatten(Node head) {
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if (head == null) {
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return null;
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}
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preOrder(head);
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dummy.next.prev = null;
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return dummy.next;
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}
23+
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private void preOrder(Node node) {
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if (node == null) {
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return;
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}
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Node next = node.next;
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Node child = node.child;
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tail.next = node;
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node.prev = tail;
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tail = tail.next;
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node.child = null;
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preOrder(child);
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preOrder(next);
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}
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}

Diff for: ‎lcof2/剑指 Offer II 028. 展平多级双向链表/Solution.py

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,33 @@
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"""
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# Definition for a Node.
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class Node:
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def __init__(self, val, prev, next, child):
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self.val = val
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self.prev = prev
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self.next = next
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self.child = child
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"""
10+
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class Solution:
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def flatten(self, head: 'Node') -> 'Node':
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if head is None:
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return None
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dummy = Node()
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tail = dummy
17+
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def preOrder(node: 'Node'):
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nonlocal tail
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if node is None:
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return
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next = node.next
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child = node.child
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tail.next = node
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node.prev = tail
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tail = tail.next
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node.child = None
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preOrder(child)
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preOrder(next)
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preOrder(head)
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dummy.next.prev = None
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return dummy.next

Diff for: ‎lcof2/剑指 Offer II 029. 排序的循环链表/README.md

+71-2
Original file line numberDiff line numberDiff line change
@@ -61,22 +61,91 @@
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<!-- 这里可写通用的实现逻辑 -->
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1. 头节点如果为空，直接返回 `node`
65+
2. 如果 `insertVal` 在链表的最小值和最大值之间，找到合适的位置插入
66+
3. 如果 `insertVal` 小于链表的最小值或大于链表的最大值，则在头节点和尾节点之间插入
67+
4. 链表的所有值和 `insertVal` 都相等，任意位置插入
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
71-
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"""
77+
# Definition for a Node.
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class Node:
79+
def __init__(self, val=None, next=None):
80+
self.val = val
81+
self.next = next
82+
"""
83+
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class Solution:
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def insert(self, head: 'Node', insertVal: int) -> 'Node':
86+
node = Node(insertVal)
87+
if head is None:
88+
node.next = node
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return node
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p = head
91+
while True:
92+
if p.val <= insertVal and insertVal <= p.next.val or \
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p.val > p.next.val and (insertVal <= p.next.val or insertVal >= p.val) or \
94+
p.next == head:
95+
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node.next = p.next
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p.next = node
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break
99+
100+
p = p.next
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return head
72102
```
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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
79-
109+
/*
110+
// Definition for a Node.
111+
class Node {
112+
public int val;
113+
public Node next;
114+
115+
public Node() {}
116+
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public Node(int _val) {
118+
val = _val;
119+
}
120+
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public Node(int _val, Node _next) {
122+
val = _val;
123+
next = _next;
124+
}
125+
};
126+
*/
127+
128+
class Solution {
129+
public Node insert(Node head, int insertVal) {
130+
Node node = new Node(insertVal);
131+
if (head == null) {
132+
node.next = node;
133+
return node;
134+
}
135+
Node p = head;
136+
for (;;) {
137+
if (p.val <= insertVal && insertVal <= p.next.val ||
138+
p.val > p.next.val && (insertVal <= p.next.val || insertVal >= p.val) ||
139+
p.next == head) {
140+
node.next = p.next;
141+
p.next = node;
142+
break;
143+
}
144+
p = p.next;
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}
146+
return head;
147+
}
148+
}
80149
```
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### **...**

Diff for: ‎lcof2/剑指 Offer II 029. 排序的循环链表/Solution.java

+40
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
1+
/*
2+
// Definition for a Node.
3+
class Node {
4+
public int val;
5+
public Node next;
6+
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public Node() {}
8+
9+
public Node(int _val) {
10+
val = _val;
11+
}
12+
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public Node(int _val, Node _next) {
14+
val = _val;
15+
next = _next;
16+
}
17+
};
18+
*/
19+
20+
class Solution {
21+
public Node insert(Node head, int insertVal) {
22+
Node node = new Node(insertVal);
23+
if (head == null) {
24+
node.next = node;
25+
return node;
26+
}
27+
Node p = head;
28+
for (;;) {
29+
if (p.val <= insertVal && insertVal <= p.next.val ||
30+
p.val > p.next.val && (insertVal <= p.next.val || insertVal >= p.val) ||
31+
p.next == head) {
32+
node.next = p.next;
33+
p.next = node;
34+
break;
35+
}
36+
p = p.next;
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}
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return head;
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}
40+
}

Diff for: ‎lcof2/剑指 Offer II 029. 排序的循环链表/Solution.py

+26
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
"""
2+
# Definition for a Node.
3+
class Node:
4+
def __init__(self, val=None, next=None):
5+
self.val = val
6+
self.next = next
7+
"""
8+
9+
class Solution:
10+
def insert(self, head: 'Node', insertVal: int) -> 'Node':
11+
node = Node(insertVal)
12+
if head is None:
13+
node.next = node
14+
return node
15+
p = head
16+
while True:
17+
if p.val <= insertVal and insertVal <= p.next.val or \
18+
p.val > p.next.val and (insertVal <= p.next.val or insertVal >= p.val) or \
19+
p.next == head:
20+
21+
node.next = p.next
22+
p.next = node
23+
break
24+
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p = p.next
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return head

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