mynode.c

图的遍历:图是由顶点集合(vertex)及顶点间的关系集合组成的一种数据结构:Graph＝( V, E ).使用拓扑排序的算法.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mynode.h"
/* Function to create an empty list 
   (the void argument list indicates that it takes no arguments) */
node_ptr create(void)
{
    node_ptr list = (node_ptr) malloc(sizeof(node_ptr));
    list->to_vertex = 0;/* superfluous initialisation */
    list->next = NULL;/* necessary initialisation to indicate last node */
    return list;
}
/* Function to return dynamically allocated memory in list */
void destroy(node_ptr list)
{
    /* Note that we don't really need to have the variable "current" here,
       as we could just advance list itself if we preferred. (Some of the other
       list functions also make use of an additional such variable.) */
    node_ptr current = list;
    while(current)
    {
        node_ptr to_free = current;
        current = current->next;
        free(to_free);
    }
    return;
        /* Note that the simpler: 
           free(current); 
           current = current->next;
           makes the mistake of using dynamically allocated memory after
           it's been freed */    
}
/* Function to insert n at front of list */
void insert_at_front(int n, node_ptr list)
{
    node_ptr new_node = (node_ptr) malloc(sizeof(struct node));
    new_node->to_vertex = n;
    new_node->next = list->next;
    list->next = new_node;
    return;
}
/* Function to print list */
void print(node_ptr list)
{
    node_ptr current = list->next;

    while(current)
    {
        printf("%d ", current->to_vertex);
        current = current->next;
    }
    printf("\n");
    return;
}
/* Function to insert n in (non-decreasing) order in list - assuming list items are already in (non-decreasing) order. */
void insert_in_order_node(int n, node_ptr list)
{
    node_ptr before = list;
    node_ptr new_node = (node_ptr) malloc(sizeof(node_ptr));
    new_node->to_vertex = n;
    /* Move along list until right place is found, looking for node after which new node should go */
    while(before->next && (before->next->to_vertex < n))
    {
        before = before->next;
    }
    new_node->next = before->next;
    before->next = new_node;
    return;
}