深入学习二叉树（03）二叉查找树

二叉查找树

它或者是一棵空树；或者是具有下列性质的二叉树：

（1）若左子树不空，则左子树上所有结点的值均小于它的根结点的值；

（2）若右子树不空，则右子树上所有结点的值均大于它的根结点的值；

（3）左、右子树也分别为二叉排序树

 创建二叉查找树

#include<stdio.h>
#include<stdlib.h>
typedef struct node{
    int value;
    struct node *lchild,*rchild,*parent;
}TreeNode;

//create Tree
TreeNode * createTree(int data[],int n){
    TreeNode *root =NULL,*p,*pre=NULL,*tag=NULL;
    int i;
    for(i=0;i<n;i++){
        p = (TreeNode *)malloc(sizeof(TreeNode));
        p->value=data[i];
        p->lchild=p->rchild=p->parent = NULL;
        if(root==NULL){        
            root = p;
        }else{
            tag = root;
            for(pre=root;pre!=NULL&&p->value<pre->value;tag=pre,pre=pre->lchild);
            for(;pre!=NULL&&p->value>=pre->value;tag=pre,pre=pre->rchild); 
            if(pre!=NULL) tag = pre;    
                
            if(p->value<tag->value){
                tag->lchild = p;
                p->parent = tag;
            }else{
                tag->rchild = p;
                p->parent = tag;
            }
        }
    }
  return root;     
}

//print
void print(TreeNode *root){
    if(root->lchild!=NULL){
        print(root->lchild);
    }
    printf("[lchild]:%8d [value]:%5d  [root]:%8d [rchild]:%8d  [parent]:%8d\n",root->lchild,root->value,root,root->rchild,root->parent);
    if(root->rchild!=NULL){
        print(root->rchild);
    }
}

int main(void){
    int data[8] = {3,2,5,8,4,7,6,9}; 
    //createTree
    TreeNode *root = createTree(data,8);
    print(root);
    return 0;
}

完整代码　

#include<stdio.h>
#include<stdlib.h>
typedef struct node{
    int value;
    struct node *lchild,*rchild,*parent;
}TreeNode;

//create Tree
TreeNode * createTree(int data[],int n){
    TreeNode *root =NULL,*p,*pre=NULL,*tag=NULL;
    int i;
    for(i=0;i<n;i++){
        p = (TreeNode *)malloc(sizeof(TreeNode));
        p->value=data[i];
        p->lchild=p->rchild=p->parent = NULL;
        if(root==NULL){        
            root = p;
        }else{
            tag = root;
            for(pre=root;pre!=NULL&&p->value<pre->value;tag=pre,pre=pre->lchild);
            for(;pre!=NULL&&p->value>=pre->value;tag=pre,pre=pre->rchild); 
            if(pre!=NULL) tag = pre;    
                
            if(p->value<tag->value){
                tag->lchild = p;
                p->parent = tag;
            }else{
                tag->rchild = p;
                p->parent = tag;
            }
        }
    }
  return root;     
}

//print
void print(TreeNode *root){
    if(root->lchild!=NULL){
        print(root->lchild);
    }
    printf("[lchild]:%8d [value]:%5d  [root]:%8d [rchild]:%8d  [parent]:%8d\n",root->lchild,root->value,root,root->rchild,root->parent);
    if(root->rchild!=NULL){
        print(root->rchild);
    }
}

int main(void){
    int data[8] = {3,2,5,8,4,7,6,9}; 
    //createTree
    TreeNode *root = createTree(data,8);
    print(root);
    return 0;
}