二叉树的建立与遍历

1：二叉树节点的定义

struct Node
{
int data;
struct Node *pleft;
struct Node *pright;
}Node;

2：二叉树创建一个节点的函数，返回值是指向该节点的指针

struct Node *createnode(int value)
{
struct Node *pnode = (struct Node *)malloc(sizeof(struct Node));
pnode->data = value;
pnode->pleft = pnode->pright = NULL;
return pnode;
}

3：二叉树插入节点

struct Node *addnode(int value, struct Node *pnode)
{
if(pnode == NULL)
return createnode(value);

if(value == pnode->data)
{
return pnode;
}

if(value < pnode->data)
{
if(pnode->pleft == NULL)
{
pnode->pleft = createnode(value);
return pnode->pleft;
}
else
{
return addnode(value, pnode->pleft);
}
}
else
{
if(pnode->pright == NULL)
{
pnode->pright = createnode(value);
return pnode->pright;
}
else
{
return addnode(value, pnode->pright);
}

}
}

4：二叉树的遍历(递归)

void listnodes(struct Node *pnode)
{
if(pnode != NULL)
{
listnodes(pnode->pleft);
printf("%d\n", pnode->data);
listnodes(pnode->pright);
}
}

5：求二叉树的深度(递归)

int Treeheight(struct Node *pnode)
{
int LD, RD;
if(pnode == NULL)
{
return 0;
}
else
{
LD = Treeheight(pnode->pleft);
RD = Treeheight(pnode->pright);
return (LD >= RD? LD:RD) + 1;
}
}

6：主函数

int main(void)
{
int newvalue = 0;
struct Node *proot = NULL;
char answer = 'n';
do
{
printf("Enter the node value:\n");
scanf("%d", &newvalue);
if(proot == NULL)
{
proot = createnode(newvalue);
}
else
{
addnode(newvalue, proot);
}
printf("\nDo you want to enter another (y or n)? ");
scanf(" %c", &answer);
} while(tolower(answer) == 'y');

listnodes(proot);
printf("\nThe height of tree is %d!", Treeheight(proot));

return 0;
}