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

typedef struct node{
    int data;
    node * lchild;
    node * rchild;
}BTree;

void createBTree(BTree * root,int x){       //建立二叉排序树
    BTree * q, * p;
    q = root;
    while(q != NULL){
        if(q->data == x){
            goto L1;
        }else if(q->data > x){
            p = q;
            q = q->lchild;
        }else{
            p = q;
            q = q->rchild;
        }
    }
    q = (BTree *)malloc(sizeof(BTree));
    q->data = x;
    q->lchild = NULL;
    q->rchild = NULL;
    if(p->data > x){
        p->lchild = q;
    }else if(p->data < x){
        p->rchild = q;
    }
L1: ;
}

BTree * searchBTree(BTree * root,int x){        //在二叉排序树中查找给定的数值，返回指向该数的指针
    BTree * q = root;
    while(q != NULL){
        if(q->data == x){
            return q;
        }else if(q->data > x){
            q = q->lchild;
        }else{
            q = q->rchild;
        }
    }
    return NULL;
}

/* 删除二叉排序树的一个结点需要考虑到： （1）空树-->退出 （2）只有一个结点并且这个结点的值与待删除结点的值一致-->将该结点的指针置空 （3）多于一个结点时，循环找到该结点并且分类考虑如何删除该结点 （3.1）该结点时叶子结点 （3.2）该结点只有左子树 （3.3）该结点只有右子树 （3.4）该结点即有左子树又有右子树 */
void deleteBTree(BTree * root,int x){
    BTree * p,* q,* r;
    q = root;
    if(q == NULL){
        goto L1;
    }else if(q->lchild == NULL && q->rchild == NULL && q->data == x){
        q = NULL;
        goto L1;
    }else{
        while(q != NULL){
            if(q->data == x){
                goto L2;
            }else if(q->data > x){
                p = q;
                q = q->lchild;
            }else{
                p = q;
                q = q->rchild;
            }
        }
        if(q == NULL){
            goto L1;
        }
    }
L1: ;
L2: if(q->lchild == NULL && q->rchild == NULL){     //当该结点是叶子结点
        if(p->lchild == q){
            p->lchild = NULL;
        }else{
            p->rchild = NULL;
        }
    }else if(q->lchild == NULL){        //当该结点只有右子树
        if(p->lchild == q){
            p->lchild = q->rchild;
        }else{
            p->rchild = q->rchild;
        }
    }else if(q->rchild == NULL){        //当该结点只有左子树
        if(p->lchild == q){
            p->lchild = q->lchild;
        }else{
            p->rchild = q->lchild;
        }
    }else{                              //当该结点即有左子树又有右子树
        r = q->rchild;
        if(r->rchild == NULL && r->lchild == NULL){     //如果待删除节点的右子树只有一个结点时，直接拷贝该值，并置该结点的右指针为空
            q->data = r->data;          
            q->rchild = NULL;
        }else{
            p = q;
            while(r->lchild != NULL){           //while循环的目的是找到该结点右子树的最左边的结点
                p = r;
                r = r->lchild;
            }
            q->data = r->data;
            if(p->lchild == r){         //当找到最左边的结点时，相当于删除一个无左子树的结点
                p->lchild = r->rchild;
            }else{
                p->rchild = r->rchild;
            }
        }
    }
}

void inOrder(BTree * root){     //中序递归遍历二叉排序树
    if(root != NULL){
        inOrder(root->lchild);
        printf("%d ",root->data);
        inOrder(root->rchild);
    }
}

int main(){
    BTree * root, * q;
    int n,x,k,t;
    printf("请输入结点的个数。\n");
    scanf("%d",&n);
    printf("请输入结点的数值。\n");
    for(int i=0;i<n;i++){
        scanf("%d",&x);
        if(i == 0){
            root = (BTree *)malloc(sizeof(BTree));
            root->data = x;
            root->lchild = NULL;
            root->rchild = NULL;
        }else{
            createBTree(root,x);
        }
    }
    printf("二叉排序树中所有的值为：\n");
    inOrder(root);
    printf("\n");
    printf("请输入要查找的数。\n");
    scanf("%d",&k);
    while(k != -1){
        q = searchBTree(root,k);
        if(q == NULL){
            printf("二叉排序树中没有该数。\n");
        }else{
            printf("找到要查找的数%d\n",q->data);
        }
        printf("请输入要查找的数。\n");
        scanf("%d",&k);
    }   
    printf("请输入要删除的数\n");
    scanf("%d",&t);
    deleteBTree(root,t);
    printf("删除后的结果是：\n");
    inOrder(root);
    return 0;
}