二叉排序链表C语言代码实现

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

typedef struct BSTNode{
    int data;
    struct BSTNode * lchild;
    struct BSTNode * rchild;
}BSTNode,* BSTree;

BSTNode * InitNode(int data){
    BSTNode * node = (BSTNode *)malloc(sizeof(BSTNode));
    if(node==NULL)exit(0);
    node->data=data;
    node->lchild=NULL;
    node->rchild=NULL;
    return node;
}


bool Insert(BSTree *tree,int data){
    BSTNode * node = InitNode(data);
    if(*tree == NULL){
       *tree= node;
       return true;
    }
    if(data<(*tree)->data){
        Insert(&((*tree)->lchild),data);
    }else{
        Insert(&((*tree)->rchild),data);
    }
}



void VisitInOrder(BSTree * tree){
    if(*tree==NULL)
    {
        printf("This is a invalid tree.");
        return;
    }
    if((*tree)->lchild !=NULL){
        VisitInOrder(&((*tree)->lchild));
    }
    printf("%d \n",(*tree)->data);
    if((*tree)->rchild !=NULL){
        VisitInOrder(&((*tree)->rchild));
    }
}

BSTNode * Query(BSTree tree,int data){
    if(tree==NULL)return NULL;
    if(tree->data == data){
       return tree;
    }
    if(data<tree->data)
    {
       return Query(tree->lchild,data);
    }
    else
    {
       return Query(tree->rchild,data);
    }
}

BSTNode * FindParent(BSTNode * tree,BSTNode * node){
    if(tree==NULL || node == NULL)return NULL;
    if((tree->lchild && tree->lchild==node)||(tree->rchild && tree->rchild == node)){
        return tree;
    }
    if(tree->lchild)return FindParent(tree->lchild,node);
    if(tree->rchild)return FindParent(tree->rchild,node);
}




bool DeleteData(BSTree* tree,int data){
    if(tree==NULL || *tree == NULL)return false;
    BSTNode * current = Query(*tree,data);
    if(current==NULL){
        printf("Data does not exist");
        return false;
    }

    BSTNode * q=NULL;
    BSTNode * s=NULL;
    if(current->lchild==NULL && current->rchild==NULL){
        if(current== *tree){//如果是根节点，直接赋值为空树即可。
           *tree=NULL;
           free(current);
           return;
        }
        BSTNode * p = FindParent(*tree ,current);//如果是叶子节点，需要找到父节点并把其child指针置空。
        if(p && p->lchild == current){
            p->lchild=NULL;
        }
        if(p && p->rchild==current){
            p->rchild=NULL;
        }
        free(current);
    }else if(current->lchild!=NULL && current->rchild==NULL){
        q=current->lchild;
        current->data=q->data;
        current->lchild=q->lchild;
        current->rchild=q->rchild;
        free(q);
    }else if(current->lchild==NULL && current->rchild!=NULL){
        q=current->rchild;
        current->data=q->data;
        current->lchild=q->lchild;
        current->rchild=q->rchild;
        free(q);
    }else{
        s=current->lchild;
        q=current;
        while(s->rchild){
            q=s;
            s=s->rchild;
        }
        current->data=s->data;
        if(current!=q){//根节点下有多层
            q->rchild=s->lchild;
        }else{//根节点下只有一层
            q->lchild=s->lchild;
        }
        free(s);
    }
}

    int main()
    {
        BSTree tree= NULL;
        int data=-1;
        printf("Entering data to create a node:\n");
        scanf("%d",&data);
        while(data!=-1){
           Insert(&tree,data);
           printf("Entering data to create a node:\n");
           scanf("%d",&data);
        }
        VisitInOrder(&tree);
        printf("enter a char to delete:\n");
        scanf("%d",&data);
        while(data!=-1){
           bool result = DeleteData(&tree,data);
           printf("delete result:%d\n",result);
           VisitInOrder(&tree);
           printf("enter a char to delete:\n");
           scanf("%d",&data);
        }
        return 0;
    }