二叉树的递归创建，二叉树查找，二叉树结点的删除代码

二叉树的递归创建

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

struct tree
{
    int data;
    struct tree* left;
    struct tree* right;
};

typedef struct tree treenode;
typedef treenode* btree;

btree createbtree(int* data,int pos)
{
    btree newnode;
    
    if(data[pos] == 0 || pos > 15)
        return NULL;
    else
    {
        newnode = (btree)malloc(sizeof(treenode));
        newnode->data = data[pos];
        
        newnode->left = createbtree(data,2*pos);
        newnode->right = createbtree(data,2*pos + 1);
        return newnode;
    }
}

void printbtree(btree ptr)
{
    if(ptr != NULL)
    {
        printbtree(ptr->left);
        printf("[%2d]",ptr->data);
        printbtree(ptr->right);
    }
}

int main()
{
    btree root = NULL;
    int i;
    
    int data[16] = {0,5,4,6,2,0,0,8,1,3,0,0,0,0,7,9};
    root = createbtree(data,1);
    printf("数组的节点内容  \n");
    for(i = 1;i < 16;i++)
        printf("[%2d]",data[i]);
    printf("\n");
    printf("树的结点内容  \n");
    printbtree(root);
    printf("\n");
    return 0;
}

使用递归创建二叉查找树，分别使用遍历和二叉查找树方式运行查找

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

struct tree
{
    int data;
    struct tree* left;
    struct tree* right;
};

typedef struct tree treenode;
typedef treenode* btree;

btree createbtree(int* data,int pos)
{
    btree newnode;
    
    if(data[pos] == 0 || pos > 15)
        return NULL;
    else
    {
        newnode = (btree)malloc(sizeof(treenode));
        newnode->data = data[pos];
        
        newnode->left = createbtree(data,2*pos);
        newnode->right = createbtree(data,2*pos + 1);
        return newnode;
    }
}

btree btreefind(btree ptr,int value)
{
    while(ptr != NULL)
    {
        if(ptr->data == value)
            return ptr;
        else
            if(ptr->data > value)
                ptr = ptr->left;
            else
                ptr = ptr->right;
    }
    return NULL;
}

btree btreesearch(btree ptr,int value)
{
    btree ptr1,ptr2;
    
    if(ptr != NULL)
    {
        if(ptr->data == value)
            return ptr;
        else
        
        ptr1 = btreesearch(ptr->left,value);
        ptr2 = btreesearch(ptr->right,value);
        if(ptr1 != NULL)
            return ptr1;
        else
            if(ptr2 != NULL)
                return ptr2;
            else
                return NULL;
    }
    else
        return NULL;
}

int main()
{
    btree root = NULL;
    btree ptr = NULL;
    int value;
    
    int data[16] = {0,5,4,6,2,0,0,8,1,3,0,0,0,0,7,9};
    root = createbtree(data,1);
    printf("请输入寻找结点数据(1-9) ==>  ");
    scanf("%d",&value);
    ptr = btreefind(root,value);
    if(ptr != NULL)
        printf("二叉查找树：结点数据是 [%d]\n",ptr->data);
    else
        printf("二叉查找树：没有找到\n");
    ptr = btreesearch(root,value);
    if(ptr != NULL)
        printf("遍历查找：结点数据是 [%d]\n",ptr->data);
    else
        printf("遍历查找：没有找到\n");
    return 0;
}

用递归创建一颗二叉树，然后输入一个结点值，找到就将结点删除

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

struct tree
{
    int data;
    struct tree* left;
    struct tree* right;
};

typedef struct tree treenode;
typedef treenode* btree;

btree createbtree(int* data,int pos)
{
    btree newnode;

    if(data[pos] == 0 || pos > 15)
        return NULL;
    else
    {
        newnode = (btree)malloc(sizeof(treenode));
        newnode->data = data[pos];

        newnode->left = createbtree(data,2*pos);
        newnode->right = createbtree(data,2*pos + 1);
        return newnode;
    }
}

btree btreefind(btree ptr,int value,int* pos)
{
    btree previous;
    
    previous = ptr;
    *pos = 0;
    while(ptr != NULL)
    {
        if(ptr->data == value)
            return previous;
        else
            previous = ptr;
            if(ptr->data > value)
            {
                ptr = ptr->left;
                *pos = -1;
            }
            else
            {
                ptr = ptr->right;
                *pos = 1;
            }
                
    }
    return NULL;
}

btree deletenode(btree root,int value)
{
    btree previous;
    btree ptr;
    btree next;
    int pos;
    
    previous = btreefind(root,value,&pos);
    if(previous == NULL)
        return root;
    switch(pos)
    {
        case -1: ptr = previous->left;
                 break;
        case 1: ptr= previous->right;
                 break;
        case 0: ptr = previous;
                 break;
    }
    
    if(ptr->left == NULL)
    {
        if(previous != ptr)
            previous->right = ptr->right;
        else
            root = root->right;
        free(ptr);
        return root;
    }
    
    if(ptr->right == NULL)
    {
        if(previous != ptr)
            previous->left = ptr->left;
        else
            root = root->left;
        free(ptr);
        return root;
    }
    
    previous = ptr;
    next = ptr->left;
    while(next->right != NULL)
    {
        previous = next;
        next = next->right;
    }
    ptr->data = next->data;
    if(previous->left == next)
        previous->left = next->left;
    else
        previous->right = next->right;
    free(next);
    return root;
}

void printbtree(btree ptr)
{
    if(ptr != NULL)
    {
        printbtree(ptr->left);
        printf("[%2d]",ptr->data);
        printbtree(ptr->right);
    }
}

int main()
{
    btree root = NULL;
    int value;

    int data[16] = {0,5,4,6,2,0,0,8,1,3,0,0,0,0,7,9};
    root = createbtree(data,1);
    printbtree(root);
    printf("\n请输入要删除的节点数据 ==> ");
    scanf("%d",&value);
    root = deletenode(root,value);
    printf("删除后树的结点内容 \n");
    printbtree(root);
    printf("\n");
    return 0;
}