我的C书中有这段代码说明了BST如何处理整数，但我的作业是关于字符串的BST。
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
struct node
{
char data;
struct node *left;
struct node *right;
};
struct node *root;
struct node *newnode(char name);
struct node *find(char key);
struct node *insert(char name);
void display(struct node *ptr);
bool rm(char key);
struct node *find_left_most(struct node *rt);
struct node *find_right_most(struct node *rt);
int main(void)
{
char ch;
char *a;
a=malloc(100*sizeof(char));
struct node *new;
root=NULL;
while(1)
{
printf("0->EXIT 1->Add name : 2->Search name : ");
printf("3->Delete name : 4->BST display :\n");
ch=getch();
switch(ch)
{
case '0':
exit(0);
case '1':
printf("name:");
scanf("%s",&a);
new=insert(a);
if (root==NULL) root=new;
if(new==NULL)
puts("There is no memory available");
break;
case '2':
printf("name:");
scanf("%s",&a);
new=find(a);
if(new!=NULL)
printf("It has been found\n");
else
printf("There is no such name\n");
break;
case '3':
printf("name:");
scanf("%s",&a);
rm(a);
break;
case '4':
display(root);
puts("");
break;
default:
puts("Wrong key");
break;
}
}
free(a);
return 0;
}
struct node *newnode(char name)
{
struct node *neos;
neos=malloc(sizeof(struct node));
neos->data = name;
neos->left = NULL;
neos->right = NULL;
return(neos);
}
void display(struct node *ptr)
{
if (ptr == NULL) return;
display(ptr->left);
printf("%s ", ptr->data);
display(ptr->right);
}
struct node *find(char key)
{
struct node *current;
current=root;
while(current->data != key)
{
if(key < current->data)
current = current->left;
else
current = current->right;
if(current == NULL)
return NULL;
}
return current;
}
struct node *insert(char name)
{
struct node *next,*current,*ptr;
bool isleft;
next=current=root;
ptr=newnode(name);
if (root == NULL)
{
return ptr;
}
while(1)
{
if(name < current->data)
{
next = current->left;
isleft=true;
}
else
{
next = current->right;
isleft=false;
}
if(next == NULL)
{
if(isleft)
current->left=ptr;
else
current->right=ptr;
return ptr;
}
current=next;
}
}
bool rm(char key)
{
struct node *current;
struct node *parent;
bool isLeftChild = true;
current=parent=root;
while(current->data != key)
{
parent = current;
if(key < current->data)
{
isLeftChild = true;
current = current->left;
}
else
{
isLeftChild = false;
current = current->right;
}
if(current == NULL)
return false;
}
if(current->left==NULL && current->right==NULL)
{
if(current == root)
root = NULL;
else if(isLeftChild)
parent->left = NULL;
else
parent->right = NULL;
}
else if(current->right==NULL)
if(current == root)
root = current->left;
else if(isLeftChild)
parent->left = current->left;
else
parent->right = current->left;
else if(current->left==NULL)
if(current == root)
root = current->right;
else if(isLeftChild)
parent->left = current->right;
else
parent->right = current->right;
else
{
struct node *successor,*temp,*old_root;
if(current == root)
{
temp=root->left;
successor=find_left_most(root->right);
root=root->right;
successor->left=temp;
}
else if(isLeftChild)
{
successor=find_left_most(current->right);
successor->left=current->left;
parent->left = current->right;
}
else
{
successor=find_right_most(current->left);
successor->right=current->right;
parent->right = current->left;
}
}
free(current);
return true;
}
//εντόπισε τον τελευταίο αριστερά κόμβο του υποδένρδου
struct node *find_left_most(struct node *rt)
{
if(rt==NULL) return NULL;
while(rt->left!=NULL)
{
rt=rt->left;
}
return rt;
}
//εντόπισε τον τελευταίο δεξιά κόμβο του υποδένρδου
struct node *find_right_most(struct node *rt)
{
if(rt==NULL) return NULL;
while(rt->right!=NULL)
{
rt=rt->right;
}
return rt;
}
我很确定自己搞砸了内存管理，这是我尝试显示Tree时程序崩溃的主要原因。更具体地说，我认为我对待“ a”变量的方式是错误的，但是我不知道该怎么办...
答案 0 :(得分：0)
您需要使用以下结构
//struct for node
struct node {
char *value; // all void* types replaced by char*
struct node *p_left;
struct node *p_right;
};
下面的插入功能用于在适当位置比较和添加数据。
//compares value of the new node against the previous node
int CmpStr(const char *a, const char *b)
{
return (strcmp (a, b)); // string comparison instead of pointer comparison
}
//inserts elements into the tree
void insert(char* key, struct node** leaf, Compare cmp)
{
int res;
if( *leaf == NULL ) {
*leaf = (struct node*) malloc( sizeof( struct node ) );
(*leaf)->value = malloc( strlen (key) +1 ); // memory for key
strcpy ((*leaf)->value, key); // copy the key
(*leaf)->p_left = NULL;
(*leaf)->p_right = NULL;
//printf( "\nnew node for %s" , key);
} else {
res = cmp (key, (*leaf)->value);
if( res < 0)
insert( key, &(*leaf)->p_left, cmp);
else if( res > 0)
insert( key, &(*leaf)->p_right, cmp);
else // key already exists
printf ("Key '%s' already in tree\n", key);
}
}
看看here了解详细代码。