c/c++ 线性表之单向循环链表

c/c++ 线性表之单向循环链表

线性表之单向循环链表

不是存放在连续的内存空间，链表中的每个节点的next都指向下一个节点，最后一个节点的下一个节点不是NULL，而是头节点。因为头尾相连，所以叫单向循环链表。

真实的第一个节点是头节点，头节点不存放数据，单纯为了编写程序方便。但是下面注释里写的【第一个节点】的含义是头节点的下一节点，也就是真实存放数据的第一个节点。

下面的代码实现了以下功能

函数	功能描述
push_back	从链表的最后插入节点
push_front	从链表的起始插入节点
show_list	打印出链表里每个节点的值
pop_back	删除链表最后一个节点
pop_front	删除链表起始节点
insert_val	在合适的位置插入一个节点； 比如原来的链表:1->3->NULL，当要插入的节点的值为2的时候，就会在1和3之间插入这个节点，插入后的链表：1->2->3->NULL
find	查找指定的节点
length	返回链表中节点的个数
delete_val	删除指定的节点
sort	排序，重新排列节点
resver	按倒序，重新排列节点
clear	释放除了头节点之外的所有节点所占用的内存空间
destroy	释放所有节点的所占用的内存空间，包括头节点

whilenode.h

#ifndef __SEQNODE__
#define __SEQNODE__

#include <stdio.h>
#include <malloc.h>
#include <assert.h>
#include <memory.h>
#include <stdbool.h>

#define ElemType int

typedef struct Node{
  ElemType data;
  struct Node* next;
}Node;

typedef struct NodeList{
  Node*  first;
  Node*  last;
  size_t size;
}NodeList;

void init(NodeList*);
void push_back(NodeList*, ElemType);
void push_front(NodeList*, ElemType);
void pop_back(NodeList*);
void pop_front(NodeList*);
void show_list(NodeList*);
void insert_val(NodeList*, ElemType);
Node* find(NodeList*, ElemType);
void delete_val(NodeList*, ElemType);
void sort(NodeList*);
void sort1(NodeList*);
void resver(NodeList*);
void resver1(NodeList*);
void resver2(NodeList*);
void clear(NodeList*);
void destroy(NodeList*);

#endif

whilenode.c

#include "seqnode.h"

void init(NodeList* list){
  list->first = (Node*)malloc(sizeof(Node));
  list->last = list->first;
  list->last->next = NULL;
  list->size = 0;
}

Node* create_node(ElemType val){
  Node* node = (Node*)malloc(sizeof(Node));
  assert(NULL != node);
  node->data = val;
  node->next = NULL;
  return node;
}
void push_back(NodeList* list, ElemType val){
  Node* p = create_node(val);

  list->last->next = p;
  list->last = p;
  list->last->next = list->first;
  list->size++;
}

void push_front(NodeList* list, ElemType val){
  Node* p = create_node(val);

  p->next = list->first->next;
  list->first->next = p;
  if(list->size == 0){
    list->last = p;
    list->last->next = list->first;
  }
  list->size++;
}

void show_list(NodeList* list){
  Node* tmp = list->first->next;
  while(tmp != list->first){
    printf("%d->", tmp->data);
    tmp = tmp->next;
  }
  printf("NULL\n");
}

void pop_back(NodeList* list){
  if(list->size == 0)return;
  Node* p = list->first;
  while(p->next != list->last){
    p = p->next;
  }
  p->next = list->first;
  free(list->last);
  list->last = p;
  list->size--;
}
void pop_front(NodeList* list){
  if(list->size == 0)return;
  Node* p = list->first->next;
  list->first->next = p->next;
  if(list->size == 1){
    list->last = list->first;
  }
  list->size--;
  free(p);
}
void insert_val(NodeList* list, ElemType val){
  if(list->size == 0){
    push_back(list, val);
    return;
  }
  Node* p = create_node(val);

  Node* t = list->first;
  while(t->next != list->first && val > t->next->data){
    t = t->next;
  }
  if(t->next == list->first){
    list->last = p;
  }
  p->next = t->next;
  t->next = p;
  
  list->size++;
}
//寻找目标节点
Node* find(NodeList* list, ElemType val){
  if(0 == list->size){
    return NULL;
  }
  Node* p = list->first->next;
  do{
    if(val == p->data){
      return p;
    }
    p = p->next;
  }
  while(list->first != p);
  return NULL;
}
//寻找目标节点的前一个节点
Node* find1(NodeList* list, ElemType val){
  if(0 == list->size){
    return NULL;
  }
  Node* p = list->first;
  do{
    if(p->next->data == val){
      return p;
    }
    p = p->next;
  }while(list->first != p);
  return NULL;
}
void delete_val(NodeList* list, ElemType val){
  if(0 == list->size)return;
 
  Node* p = find1(list, val);
  if(NULL == p)return;
  if(p->next == list->last){
    list->last = p;
  }
  Node* tmp = p->next;
  p->next = p->next->next;
  free(tmp);
  list->size--;
}

void sort(NodeList* list){
  if(list->size == 0 || list->size == 1)return;

  Node* p = list->first->next;

  Node* t = list->last = list->first;
  list->last->next = list->first;

  size_t s = list->size;

  while(s-- > 0){
    while(p->data > t->next->data && t->next != list->first){
      t = t->next;
    }
    if(t->next == list->first){
      list->last = p;
    }

    Node* tmp = p->next;
    p->next = t->next;
    t->next = p;

    p = tmp;
    t = list->first;
  }
  list->last->next = list->first;
}
void resver(NodeList* list){
  if(list->size == 0 || list->size == 1)return;

  Node* head = list->first->next;
  Node* end = head;

  list->last = list->first;
  list->last->next = list->first;
  
  while(head != list->first){
    Node* tmp = head->next;
  
    head->next = list->first->next;
    list->first->next = head;
    
    head = tmp;
  }
  list->last = end;
}

void clear(NodeList* list){
  if(list->size == 0) return;
  Node* b = list->first->next;
  Node* q;
  while(b != list->first){
    q = b->next;
    free(b);
    b = q;
  }
  list->last = list->first;
  list->last->next = list->first;
  list->size = 0;
}

void destroy(NodeList* list){
  Node* b = list->first;
  Node* q;
  while(b != list->first){
    q = b->next;
    free(b);
    b = q;
  }
}

whilenodemain.c

#include "seqnode.h"

int main(){
  NodeList list;
  init(&list);
  int select = 1;
  ElemType item;
  Node* node = NULL;
  while(select){
    printf("*****************************************\n");
    printf("*** [1]   push_back   [2]  push_front ***\n");
    printf("*** [3]   show_list   [4]  pop_back   ***\n");
    printf("*** [5]   pop_front   [6]  insert_val ***\n");
    printf("*** [7]   find        [8]  length     ***\n");
    printf("*** [9]   delete_val  [10] sort       ***\n");
    printf("*** [11]  sort        [12] resver     ***\n");
    printf("*** [13]              [14] clear      ***\n");
    printf("*** [0]   quit        [15*]destroy    ***\n");
    printf("*****************************************\n");
    printf("请选择:>");
    scanf("%d", &select);
    if(0 == select)
      break;
    switch(select){
    case 1:
      printf("请输入要插入的数据,以-1结束>\n");
      while(scanf("%d",&item) && item != -1){
	push_back(&list, item);
      }
      show_list(&list);
      break;
    case 2:
      printf("请输入要插入的数据,以-1结束>\n");
      while(scanf("%d", &item) && item != -1){
	push_front(&list, item);
      }
      show_list(&list);
      break;
    case 3:
      show_list(&list);
      break;
    case 4:
      pop_back(&list);
      show_list(&list);
      break;
    case 5:
      pop_front(&list);
      show_list(&list);
      break;
    case 6:
      printf("请输入要插入的数据>\n");
      scanf("%d",&item);
      insert_val(&list, item);
      show_list(&list);
      break;
    case 7:
      printf("please enter what you shoule find out>\n");
      scanf("%d",&item);
      node = find(&list, item);
      if(node == NULL){
	printf("can not find %d\n", item);
      }
      break;
    case 8:
      printf("length is %ld\n", list.size);
      break;
    case 9:
      printf("please enter what you want to delete>\n");
      scanf("%d",&item);      
      delete_val(&list, item);
      show_list(&list);
      break;
    case 10:
      // sort(&list);
      //show_list(&list);
      break;
    case 11:
      sort(&list);
      show_list(&list);
      break;
    case 12:
      resver(&list);
      show_list(&list);
      break;
    case 13:
      resver(&list);
      show_list(&list);
      break;
    case 14:
      clear(&list);
      show_list(&list);
      break;
    case 15:
      destroy(&list);
      break;
    default:
      break;
    }
  }

  destroy(&list);
}