python 双向链表_python算法与数据结构-双向链表(40)
一、雙向鏈表的介紹
一種更復(fù)雜的鏈表是“雙向鏈表”或“雙面鏈表”。每個(gè)節(jié)點(diǎn)有兩個(gè)鏈接:一個(gè)指向前一個(gè)節(jié)點(diǎn),當(dāng)此節(jié)點(diǎn)為第一個(gè)節(jié)點(diǎn)時(shí),指向空值;而另一個(gè)指向下一個(gè)節(jié)點(diǎn),當(dāng)此節(jié)點(diǎn)為最后一個(gè)節(jié)點(diǎn)時(shí),指向空值。雙向鏈表結(jié)構(gòu)圖
上圖是雙向鏈表的結(jié)構(gòu)圖,即通過(guò)上一個(gè)節(jié)點(diǎn)可以找到下一個(gè),通過(guò)下一個(gè)也可以找到上一個(gè)節(jié)點(diǎn)。
二、雙向鏈表插入和刪除的圖解
1、插入圖解插入圖解
2、刪除圖解刪除圖解
三、雙向鏈表的python代碼實(shí)現(xiàn)# 1、創(chuàng)建節(jié)點(diǎn)
class Node(object):
# 初始化方法
def __init__(self, item):
self.item= item
self.next = None
self.prev = None
# 2、創(chuàng)建循環(huán)鏈表
class DoubleLinKList(object):
# 初始化方法
def __init__(self):
self._head = None
# 3、判斷是否為空
def is_empty(self):
"""判斷鏈表是否為空"""
return self._head == None
# 4、求其長(zhǎng)度
def length(self):
"""返回鏈表的長(zhǎng)度"""
cur = self._head
count = 0
while cur != None:
count += 1
cur = cur.next
return count
# 遍歷
def travel(self):
"""遍歷鏈表"""
print("你要遍歷的鏈表元素有:",end=" ")
cur = self._head
while cur != None:
print("%s "%cur.item,end=" ")
cur = cur.next
print("")
# 5、頭插
def add(self, item):
"""頭部插入元素"""
node = Node(item)
if self.is_empty():
# 如果是空鏈表,將_head指向node
self._head = node
else:
# 將node的next指向_head的頭節(jié)點(diǎn)
node.next = self._head
# 將_head的頭節(jié)點(diǎn)的prev指向node
self._head.prev = node
# 將_head 指向node
self._head = node
# 6、尾插
def append(self, item):
"""尾部插入元素"""
node = Node(item)
if self.is_empty():
# 如果是空鏈表,將_head指向node
self._head = node
else:
# 移動(dòng)到鏈表尾部
cur = self._head
while cur.next != None:
cur = cur.next
# 將尾節(jié)點(diǎn)cur的next指向node
cur.next = node
# 將node的prev指向cur
node.prev = cur
# 7、查找
def search(self, item):
"""查找元素是否存在"""
cur = self._head
while cur != None:
if cur.item == item:
return True
cur = cur.next
return False
# 8、指定位置插入
def insert(self, pos, item):
"""在指定位置添加節(jié)點(diǎn)"""
if pos <= 0 or pos>self.length()+1 :
print("你輸入的位置有誤,請(qǐng)重新輸入")
elif pos == 1:
self.add(item)
elif pos == self.length()+1:
self.append(item)
else:
node = Node(item)
cur = self._head
count = 1
# 移動(dòng)到指定位置的前一個(gè)位置
while count < (pos - 1):
count += 1
cur = cur.next
# 將node的prev指向cur
node.prev = cur
# 將node的next指向cur的下一個(gè)節(jié)點(diǎn)
node.next = cur.next
# 將cur的下一個(gè)節(jié)點(diǎn)的prev指向node
cur.next.prev = node
# 將cur的next指向node
cur.next = node
# 9、刪除
def remove(self, item):
"""刪除元素"""
if self.is_empty():
return
else:
cur = self._head
if cur.item == item:
# 如果首節(jié)點(diǎn)的元素即是要?jiǎng)h除的元素
if cur.next == None:
# 如果鏈表只有這一個(gè)節(jié)點(diǎn)
self._head = None
else:
# 將第二個(gè)節(jié)點(diǎn)的prev設(shè)置為None
cur.next.prev = None
# 將_head指向第二個(gè)節(jié)點(diǎn)
self._head = cur.next
return
while cur != None:
if cur.item == item:
# 將cur的前一個(gè)節(jié)點(diǎn)的next指向cur的后一個(gè)節(jié)點(diǎn)
cur.prev.next = cur.next
# 將cur的后一個(gè)節(jié)點(diǎn)的prev指向cur的前一個(gè)節(jié)點(diǎn)
cur.next.prev = cur.prev
break
cur = cur.next
# 驗(yàn)證
if __name__ == '__main__':
double_link = DoubleLinKList()
# 頭插
double_link.add(1)
# 遍歷
double_link.travel()
# 尾插
double_link.append(2)
double_link.travel()
# 按照索引插入
double_link.insert(3,4)
double_link.travel()
double_link.insert(3,3)
double_link.travel()
# 刪除
double_link.remove(3)
double_link.travel()
運(yùn)行結(jié)果為:你要遍歷的鏈表元素有: 1
你要遍歷的鏈表元素有: 1 2
你要遍歷的鏈表元素有: 1 2 4
你要遍歷的鏈表元素有: 1 2 3 4
你要遍歷的鏈表元素有: 1 2 4
四、雙向鏈表的C語(yǔ)言代碼實(shí)現(xiàn)// main.m
// 雙向鏈表
// Created by 侯壘 on 2019/6/28.
// Copyright ? 2019 可愛(ài)的侯老師. All rights reserved.
#import
typedef struct N
{
int element;
struct N *next;
struct N *prev;
}Node;
// 創(chuàng)建節(jié)點(diǎn)
Node *createNode(int num)
{
Node *node = (Node *)malloc(sizeof(Node));
node->element = num;
node->next = NULL;
node->prev = NULL;
return node;
}
// 創(chuàng)建雙向鏈表
Node *createDoubleLinkList(Node *node)
{
Node *head = node;
return head;
}
// 判斷是否為空
int is_empty(Node *head)
{
if (head == NULL)
{
return 1;
}
else
{
return 0;
}
}
// 求其長(zhǎng)度
int length(Node *head)
{
Node *current = head;
int count = 0;
while (current != NULL)
{
count++;
current = current->next;
}
return count;
}
// 遍歷
void travel(Node *head)
{
printf("你要遍歷的數(shù)據(jù)有:");
Node *current = head;
while (current != NULL)
{
printf("%d ",current->element);
current = current->next;
}
printf("\n");
}
// 頭插
Node * add(Node *head,int num)
{
Node *node = createNode(num);
if (is_empty(head)==1)
{
head = node;
}
else
{
node->next = head;
head->prev = node;
head = node;
}
return head;
}
// 尾插
Node* append(Node *head,int num)
{
Node *node = createNode(num);
if (is_empty(head)==1)
{
head = node;
}
else
{
Node *current = head;
while (current->next != NULL)
{
current = current->next;
}
current->next = node;
node->prev = current;
}
return head;
}
// 查找
int search(Node *head,int num)
{
Node *current = head;
for (int i=0; i
{
if (current->element == num)
{
return i+1;
}
current = current->next;
}
return 0;
}
// 按指定位置插入
Node * insert(Node *head ,int index,int num)
{
if (index<=0||index>length(head)+1)
{
printf("你要插入的位置不對(duì),請(qǐng)重新插入");
}
else if (index == 1)
{
head = add(head, num);
}
else if (index == length(head)+1)
{
append(head, num);
}
else
{
Node *node = createNode(num);
Node *current = head;
for (int i=1; i
{
current = current->next;
}
node->prev = current;
node->next = current->next;
current->next->prev = node;
current->next = node;
}
return head;
}
// 刪除元素
Node * removeNode(Node *head,int num)
{
if (is_empty(head)==1)
{
printf("你要?jiǎng)h除的鏈表為空");
}
else
{
Node *current = head;
//處理頭結(jié)點(diǎn)就是要?jiǎng)h除的節(jié)點(diǎn)
if (current->element == num)
{
if (current->next == NULL)
{
// 只有首節(jié)點(diǎn)這一個(gè)元素
head = NULL;
}
else
{
// 要?jiǎng)h除的是首節(jié)點(diǎn),但是后面還有元素
current->next->prev = NULL;
head = current->next;
}
}
else
{
while (current!=NULL)
{
if (current->element == num)
{
current->prev->next = current->next;
current->next->prev = current->prev;
break;
}
current = current->next;
}
}
}
return head;
}
int main(int argc, const char * argv[]) {
// 創(chuàng)建節(jié)點(diǎn)
Node *node = createNode(1);
// 創(chuàng)建鏈表
Node *head = createDoubleLinkList(node);
// 驗(yàn)證遍歷
travel(head);
// 驗(yàn)證頭插
head = add(head, 0);
travel(head);
// 驗(yàn)證尾插
head = append(head, 3);
travel(head);
// 驗(yàn)證查找
int index = search(head, 1);
if (index != 0)
{
printf("你要查找的數(shù)據(jù)在%d位置\n",index);
}
else
{
printf("沒(méi)有找到你要的數(shù)據(jù)\n");
}
//驗(yàn)證按指定位置插入
head = insert(head, 2, 2);
travel(head);
//驗(yàn)證刪除
head = removeNode(head, 0);
travel(head);
return 0;
}
運(yùn)行結(jié)果為:你要遍歷的數(shù)據(jù)有:1
你要遍歷的數(shù)據(jù)有:0 1
你要遍歷的數(shù)據(jù)有:0 1 3
你要查找的數(shù)據(jù)在2位置
你要遍歷的數(shù)據(jù)有:0 2 1 3
你要遍歷的數(shù)據(jù)有:2 1 3
侯哥語(yǔ)錄:我曾經(jīng)是一個(gè)職業(yè)教育者,現(xiàn)在是一個(gè)自由開(kāi)發(fā)者。我希望我的分享可以和更多人一起進(jìn)步。分享一段我喜歡的話給大家:"我所理解的自由不是想干什么就干什么,而是想不干什么就不干什么。當(dāng)你還沒(méi)有能力說(shuō)不得時(shí)候,就努力讓自己變得強(qiáng)大,擁有說(shuō)不得權(quán)利。"
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