[英]Delete function for binary tree
给定以下代码,我可以使用什么来执行删除功能? 我已经尝试了多种方法,但是我一直在努力使其工作而陷入困境。 我的主要问题是尝试删除具有左右子节点的节点。 对于没有子节点的节点,我可以将其父节点设置为指向null并释放该节点。 对于一个孩子,只需将父对象设置为指向该孩子并释放节点即可。 从概念上和代码上,对于有两个孩子的节点,我将如何处理?
#include<stdlib.h>
#include<stdio.h>
struct bin_tree {
int data;
struct bin_tree * right, * left;
} bin_tree;
typedef struct bin_tree node;
void help()//help
{
printf("Options:\n");
printf(" # -Put in any number to add it to the tree if not already there\n");
printf(" s # -Put in s and a number to search the tree for the number\n");
printf(" d # -Delete the number from the tree\n");
printf(" p -Put in p to print the tree\n");
printf(" ? -At any time you can press ? to display the help message\n");
printf(" Q -If you decide the leave the realm of the tree then you can press Q to quit this program\n");
}
int max(int a,int b)//max tree length
{
if(a>b)
return a;
else
return b;
}
int height(node* tree)//height
{
if(tree != NULL)
return(1 + max(height(tree->left),height(tree->right)));
else
return 0;
}
void insert(node ** tree, int val)//insert
{
node *temp = NULL;
if(!(*tree))
{
temp = (node *)malloc(sizeof(node));
temp->left = temp->right = NULL;
temp->data = val;
*tree = temp;
return;
}
if(val < (*tree)->data)
{
insert(&(*tree)->left, val);
}
else if(val > (*tree)->data)
{
insert(&(*tree)->right, val);
}
}
void print(node * tree)//print
{
if (tree)
{
print(tree->left);
printf("[%d] ",tree->data);
print(tree->right);
}
}
node* search(node ** tree, int val)
{//search
if(!(*tree))
{
return NULL;
}
if(val < (*tree)->data)
{
search(&((*tree)->left), val);
}
else if(val > (*tree)->data)
{
search(&((*tree)->right), val);
}
else if(val == (*tree)->data)
{
return *tree;
}
}
void main()
{
node *root;
node *tmp;
int no;
char ch, buff[500];
root = NULL;
printf("Options:\n");
printf(" # -Put in any intiger to add it to the tree if not already there\n");
printf(" s # -Put in s and a number to search the tree for the number\n");
printf(" d # -Delete the number from the tree\n");
printf(" p -Print the tree\n");
printf(" ? -At any time you can press ? to display the help message\n");
printf(" Q -If you decide the leave the realm of the tree then you can press Q to quit this program\n");
while(1){
printf(">");
fgets(buff,499,stdin); //grabs input from user
if(sscanf(buff,"%i",&no)==1){//decides if just a number
tmp = search(&root, no);//looks for number in the tree
if (tmp)
{
printf("Node already in tree!\n", tmp->data);
}
else
{
insert(&root, no);//if not in tree insert it
}
}
else if(sscanf(buff,"%c %i",&ch,&no)>=1)//checks if character
{
switch(ch)
{
case 's'://search for number
{
tmp = search(&root, no);
if (tmp)
{
printf("Node found=%d\n", tmp->data);
}
else
{
printf("Node not found in tree.\n");
}
break;
}
case 'd':
tmp = search(&root, no);
if (tmp)
{
//Call delete function
printf("Node %i deleted", no);
break;
}
else
{
printf("Node not found in tree.\n");
break;
}
case 'Q'://quit
exit(0);
case 'p'://print tree
printf("\n\n");
print(root);
printf("\nHeight= %i\n\n",height(root));
break;
case '?'://display help
help();
break;
default://idiot >.>
printf("Invalid input!\n\n");
help();
break;
}
}
}
return;
}
左侧的最大节点或右侧的最小节点都将占据它的位置!
只需将其中之一放在删除的节点所在的位置(并将它们从以前的位置delete
),您的树仍将是有效的二进制搜索树。 看一下这个例子:
15
/ \
… 25
/ \
20 30
\
23
假设您要删除节点25
:
15
),因此使用其中之一代替25
是有效的。 ✓ 23
)中选择最大的节点,则该节点将大于左侧的任何节点,但也小于右侧的任何节点,因此非常适合中间和中间可以代替已删除的节点。 ✓ 30
)的最小节点来说也是如此。 ✓ 如果所选节点是叶子,则一切都很好,您可以将其删除。 否则,请在所选节点上执行delete
操作。
您也可以查看二进制搜索树的Wikipedia文章,了解伪代码的实现。
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