如何在c中创建一个n元树 [英] how to create a n-ary tree in c

问题描述

#include <stdio.h>
#include <stdlib.h>


struct node{
  char *word;
  int depth, children;
  struct node  **child;
};

typedef struct node node;


node *createTree();
node *createNode(char *word,int depth);

int main(int argv,char *argc[]){
   node *root,*current_node;
   root=createNode("root",0);
   char *array[]={"string1","string2","string3"};
   current_node=root;
   printf("root has been created with word: %s 
",current_node->word);
   int i;
   for (i=0; i<3; i++){
      current_node->child[i]=createNode(array[i],(current_node->depth)+1);
      current_node->children++;
      printf("%s  has been inserted to the tree
",current_node->word);
   }

}



node *createTree(){
   printf("root has been created
");
   return createNode("",0);    /*creates the first node*/
}

node *createNode(char *word,int depth){
   node *new_node;
   new_node=malloc(sizeof(node));
   new_node->word=word;
   new_node->depth=depth;
   new_node->children=0;
   new_node->child=NULL;
}

所以我在这里要做的是构建一个 n 叉树.我使用 createNode 函数来创建根的子节点，但是一旦我尝试将新节点的地址链接到子节点，程序就会因分段错误而崩溃.我知道我的错误可能是，我尝试创建孩子的方式，但我找不到.帮助任何人?

So what i am trying to do here is build a n-ary tree. I use createNode function to create the children of the root but as soon as i am trying to link an adress of a new node to a child, the program crashes with segmentation fault. I know my mistake probably is,the way i try to create the children but i cant find. Help anyone?

推荐答案

只需为 child struct 成员分配内存，然后再使用:

Just allocate memory for the child struct member before using it:

current_node->child = malloc(3 * sizeof(node *));

for (i=0; i<3; i++) {
    current_node->child[i] = createNode(array[i],(current_node->depth)+1);
    current_node->children++;
    printf("%s  has been inserted to the tree
",current_node->word);
}

您定义的结构意味着您必须将每个级别作为具有潜在动态元素数量的节点数组进行管理.C 中用于 n 元树表示的更常见结构是:

The structure you've defined means you have to manage each level as an array of nodes with a potentially dynamic number of elements. A more common structure used for n-ary tree representation in C would be:

struct node {
    char *word;
    int depth, children;  // Reconsider if you need these
                          //   for maintenance effort versus benefit
    struct node *child;   // point to children of this node
    struct node *next;    // point to next node at same level
};

所以结构看起来像这样:

So the structure looks like this:

Root -> NULL
 |
 V
Child-1.1 -> Child-1.2 -> ... -> Child-1.n -> NULL
 |              |                   |            
 |              V                   V
 |              ...              Child-1.n.1 -> ... -> NULL
 V
Child-1.1.1 -> Child-1.1.2 -> ... -> NULL
 |
 ... etc

然后您需要修改您的 createNode 并相应地编写其他树管理例程.部分且非常简洁的示例(不一定包含所有正确的有效性检查或节点删除/解除分配):

You'd then need to modify your createNode and write your other tree management routines accordingly. A partial and very terse sample of how they might look would be (not necessarily containing all the right validity checks or node removal/deallocations):

struct node {
    int data;
    struct node *next;
    struct node *child;
};

typedef struct node node;

node * new_node(int);
node * add_sibling(node *, int);
node * add_child(node *, int);

int main(int argc, char *argv[])
{
    int i;
    node *root = new_node(0);

    for ( i = 1; i <= 3; i++ )
        add_child(root, i);
}

node * new_node(int data)
{
    node *new_node = malloc(sizeof(node));

    if ( new_node ) {
        new_node->next = NULL;
        new_node->child = NULL;
        new_node->data = data;
    }

    return new_node;
}

node * add_sibling(node * n, int data)
{
    if ( n == NULL )
        return NULL;

    while (n->next)
        n = n->next;

    return (n->next = new_node(data));
}

node * add_child(node * n, int data)
{
    if ( n == NULL )
        return NULL;

    if ( n->child )
        return add_sibling(n->child, data);
    else
        return (n->child = new_node(data));
}

这篇关于如何在c中创建一个n元树的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！