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数据结构——图的链表实现
图的链表实现
之前实现了图的数组实现
http://blog.csdn.net/cinmyheart/article/details/41370465
下图仅作示意性说明，和测试数据有点区别，测试数据还是用的原来数组实现时的测试数据，这并不影响图的数据结构的表示(其实我就是懒得再做一遍原始数据了。。。哈哈)
现对图进行抽象，对于整个图，我用了结构体struct graph,图中有节点，那么节点我用struct vertex 进行抽象，至于struct vertex adjacent[0]这个技巧是我常用的伎俩
不熟悉或者不知道的话可以看这里
http://blog.csdn.net/cinmyheart/article/details/28985843
这里我想强调一下的就是，权衡了一下，在struct vertex内部我使用了两个指针,一个end 一个next，实质上，看代码就知道，只有头节点会同时用到end和next两个指针，end的存在是为了最快速的跳转指向到链表末尾，然而，除开头节点外，其他节点的end是没有意义的，代码里面其他节点也没有使用end指针。这里是一种权衡考虑，为了最快的跳转到链表末尾，我选择了牺牲一点内存(用来储存end指针的).
/************************************************************
code file : graph.h
code writer : EOF
code date : 2014.11.22
e-mail : jasonleaster@gmail.com
code description:
This file is a header file for out test program.
We abstract the data structure -- Graph here. And we also
declare some useful API to construct out naive graph :)
************************************************************/
#ifndef _GRAPH_LIST_H
#define _GRAPH_LIST_H
#include <stdio.h>
#include <stdlib.h>
#define CONNECTED 1
#define DISCONNECTED 0
#define SUCCESS 0
#define FAILED -1
struct vertex
{
int value;
struct vertex* next;
struct vertex* end;
};
struct graph
{
int num_vertex;
int num_edge;
struct vertex adjacent[0];
};
struct graph* init_graph(int vertex,int edge);
void release_graph(struct graph* p_graph);
int add_edge(struct graph* p_graph,char from_v,char to_v);
int print_graph(struct graph* p_graph);
#endif对于数据数据结构进行初始化
/************************************************************
code file : init_graph.c
code writer : EOF
code date : 2014.11.22
e-mail : jasonleaster@gmail.com
code description:
This function is used for initializing the graph
with inputed parameter @vertex and @edge.
************************************************************/
#include "graph_list.h"
struct graph* init_graph(int num_vertex,int num_edge)
{
if(num_vertex <= 0 || num_edge <= 0)
{
return NULL;
}
struct graph* p_graph = NULL;
p_graph = (struct graph*)malloc(sizeof(struct graph) + num_vertex*sizeof(struct vertex));
if(!p_graph)
{
printf("malloc failed in function %s()\n",__FUNCTION__);
return NULL;
}
p_graph->num_vertex = num_vertex;
p_graph->num_edge = num_edge;
int temp = 0;
//initialize the adjacent relationship
for(temp = 0;temp < num_vertex;temp++)
{
p_graph->adjacent[temp].value = http://www.mamicode.com/temp;>这里开始真正的建立图节点间的链接关系这里注意到，由于图是双向连同的图，而不是单向的，因此建立A-B关系的时候还要建立B-A关系
/************************************************************
code file : add_edge.c
code writer : EOF
code date : 2014.11.22
e-mail : jasonleaster@gmail.com
code description:
This function will help us to add a new connection
between different vertex which is in the graph.
*************************************************************/
#include "graph_list.h"
int add_edge(struct graph* p_graph,char from_v,char to_v)
{
if(!p_graph || from_v < 0 || to_v < 0)
{
return FAILED;
}
struct vertex* p_to_v = (struct vertex*)malloc(sizeof(struct vertex));
struct vertex* p_from_v = (struct vertex*)malloc(sizeof(struct vertex));
if(!p_to_v || !p_from_v)
{
printf("malloc failed in function %s()\n",__FUNCTION__);
return FAILED;
}
if(!(p_graph->adjacent[from_v].end))
{
p_graph->adjacent[from_v].next = p_to_v;
p_graph->adjacent[from_v].end = p_to_v;
p_to_v->next = NULL;
p_to_v->value = http://www.mamicode.com/to_v;>
链表实现时候，图的释放会有点不“优雅”。
节点在内存中离散的分布导致释放时要一个个释放。如果是数组实现的话，一次性就ＯＫ了
/************************************************************
code file : release_graph.c
code writer : EOF
code date : 2014.11.22
e-mail : jasonleaster@gmail.com
code description:
It's easy and convenient for us to call this API once
and free all the graph.
*************************************************************/
#include "graph_list.h"
void release_graph(struct graph* p_graph)
{
if(!p_graph)
{
return ;
}
int temp = 0;
int num_vertex = p_graph->num_vertex;
struct vertex* p_temp = NULL;
for(temp = 0;temp < num_vertex;temp++)
{
if(p_graph->adjacent[temp].next)
{
p_temp = (p_graph->adjacent[temp].next->next);
while(p_temp)
{
free(p_graph->adjacent[temp].next);
p_graph->adjacent[temp].next = p_temp;
p_temp = p_temp->next;
}
free(p_graph->adjacent[temp].next);
}
}
free(p_graph);
}
打印图节点间的关系
/************************************************************
code file : print_graph.c
code writer : EOF
code date : 2014.11.22
e-mail : jasonleaster@gmail.com
code description:
This function will print out the connection of graph
which @p_graph point to.
************************************************************/
#include "graph_list.h"
int print_graph(struct graph* p_graph)
{
if(!p_graph)
{
return FAILED;
}
int from_v = 0;
int to_v = 0;
int num_vertex = p_graph->num_vertex;
struct vertex* p_vertex = NULL;
for(from_v = 0;from_v < num_vertex;from_v++)
{
p_vertex = &(p_graph->adjacent[from_v]);
while(p_vertex)
{
printf("\t%d",p_vertex->value);
p_vertex = p_vertex->next;
}
printf("\n");
}
return SUCCESS;
}
测试主程序
/****************************************************************
code file : test_graph.c
code writer : EOF
code date : 2014.11.22
e-mail : jasonleaster@gmail.com
code description:
Here , we use this program to call some API which would
construct a ADT--graph and test it.
*****************************************************************/
#include <stdio.h>
#include "graph_list.h"
int main()
{
struct graph* p_graph = NULL;
FILE* fp = fopen("./text.txt","r+");
if(!fp)
{
printf("fopen() failed!\n");
return 0;
}
int ret = 0;
int vertex = 0;
int edge = 0;
int from_v = 0;
int to_v = 0;
fscanf(fp,"%d",&vertex);
fscanf(fp,"%d",&edge);
p_graph = init_graph(vertex,edge);
int temp = 0;
for(temp;temp < edge;temp++)
{
/*
** I think it's necessary to check the returned value
** of scanf() family.
*/
ret = fscanf(fp,"%d %d",&from_v,&to_v);
if(ret != 2)
{
break;
}
add_edge(p_graph,from_v,to_v);
}
print_graph(p_graph);
release_graph(p_graph);
fclose(fp);
return 0;
}测试文本 text.txt
13
13
0 5
4 3
0 1
9 12
6 4
5 4
0 2
11 12
9 10
0 6
7 8
9 11
5 3
测试结果：
数据结构——图的链表实现
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