C 树不';不要长得超过3号
我试图在二叉搜索树中实现插入子例程,每个节点都有一个单词(字符串)作为键。 我从STDIN中提取单词,并使用insert函数插入它们。但每当我按顺序遍历时,我发现树的长度不会超过3个节点。有什么不对劲?我的代码附在这里:C 树不';不要长得超过3号,c,binary-search-tree,C,Binary Search Tree,我试图在二叉搜索树中实现插入子例程,每个节点都有一个单词(字符串)作为键。 我从STDIN中提取单词,并使用insert函数插入它们。但每当我按顺序遍历时,我发现树的长度不会超过3个节点。有什么不对劲?我的代码附在这里: typedef struct treenode { char word[20]; //word is the key for each node struct treenode *left; struct treenode *right;
typedef struct treenode
{
char word[20]; //word is the key for each node
struct treenode *left;
struct treenode *right;
} treenode;
treenode *insert (treenode *node, char *word)
{
if(node==NULL) //if a null node is reached,make a temp node and append it
{
treenode *temp;
temp = (treenode *) malloc(sizeof(treenode));
strcpy (temp ->word,word);
temp-> left = NULL;
temp-> right = NULL;
return temp;
}
if ((strcmp(word, node ->word)>0)) //if the key is greater than node.word,go to right child
{
node-> right = insert(node-> right, word);
}
else if(strcmp(word,node->word)<=0) //if key <node.word,go to left child
{
node-> left = insert(node-> left, word);
}
}
void printinorder(treenode *node)
{
if(node == NULL) return;
printinorder(node-> left);
printf("%s ",node-> word);
printinorder(node-> right);
}
int main()
{
treenode *root = NULL;
char string[20];
scanf("%s",string); //first input is taken once here and once again inside loop,but its OK
root = insert(root, string+1); //duplicate entries are also stored
while(strcmp(string,".")!=0) //input is terminated by a full stop
{
insert(root, string+1);
scanf("%s",string);
}
printinorder(root); //finally printing the BST
return 0;
}
typedef结构树节点
{
char word[20];//word是每个节点的键
结构树节点*左;
结构树节点*右侧;
}三烯醇;
树节点*插入(树节点*节点,字符*字)
{
if(node==NULL)//如果到达NULL节点,则创建一个临时节点并附加它
{
treenode*温度;
temp=(treenode*)malloc(sizeof(treenode));
strcpy(临时->单词,单词);
temp->left=NULL;
temp->right=NULL;
返回温度;
}
if((strcmp(word,node->word)>0))//如果键大于node.word,则转到右侧子项
{
节点->右侧=插入(节点->右侧,word);
}
else if(strcmp(字,节点->字)左,字);
}
}
无效打印顺序(treenode*节点)
{
if(node==NULL)返回;
打印顺序(节点->左侧);
printf(“%s”,节点->单词);
打印顺序(节点->右侧);
}
int main()
{
treenode*root=NULL;
字符串[20];
scanf(“%s”,string);//第一个输入在这里进行一次,在循环中进行一次,但它是确定的
root=insert(root,string+1);//还存储重复的条目
while(strcmp(string,“.”!=0)//输入以句号终止
{
插入(根,字符串+1);
scanf(“%s”,字符串);
}
printinorder(root);//最后打印BST
返回0;
}
实现中的问题是,您试图将创建_节点
和插入
组合到单个函数中,然后将该单个函数用作树初始化和插入的通用解决方案。在这里,它导致了insert
返回类型的复杂性(如注释中所述),并可能导致您错过insert
中所需的递归。(注意在插入的树->右
和树->左
下添加和一个else
)
最好将create_节点
和insert
例程拆分为单独的函数。这允许将create\u节点
定义为类型treenode
,将insert
定义为类型void
。这简化了每种方法的代码,并使遵循逻辑更容易、更可读。这样,您的代码就会变成:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct treenode
{
char word[20]; //word is the key for each node
struct treenode *left;
struct treenode *right;
} treenode;
treenode* create_node (char *word)
{
treenode* tmp = malloc (sizeof (struct treenode));
if (tmp) {
strcpy (tmp ->word,word);
tmp->left = NULL;
tmp->right = NULL;
} else {
fprintf (stderr, "%s() error: memory exhausted\n", __func__);
}
return tmp;
}
void insert (treenode *tree, char *word)
{
if (strcmp (word, tree->word) > 0)
{
if (tree->right == NULL) {
tree->right = create_node (word);
insert (tree->right, word);
} else {
insert (tree->right, word);
}
}
else if (strcmp (word, tree->word) < 0)
{
if (tree->left == NULL) {
tree->left = create_node (word);
insert (tree->left, word);
} else {
insert (tree->left, word);
}
}
}
void printinorder(treenode *node)
{
if(node == NULL) return;
printinorder(node-> left);
printf("%s ",node-> word);
printinorder(node-> right);
}
int main()
{
treenode *root = NULL;
char string[20];
scanf ("%s",string); //first input is taken once here and once again inside loop,but its OK
root = create_node (string); //duplicate entries are also stored
while (strcmp (string,".")!=0) //input is terminated by a full stop
{
insert (root, string);
scanf ("%s",string);
}
printinorder(root); //finally printing the BST
return 0;
}
此外,如评论中所述-请勿播放malloc。这是不必要的,而且会增加出错的可能性。您可能希望在这件事的底部找到回报。和.尝试调试器并查看*insert()
@WhozCraig谢谢,返回成功。
$ gcc -Wall -Wextra -o bst bst.c
$ ./bst
my_dog
has
fleas
my_cat
likes
snakes
.
fleas has likes my_cat my_dog snakes