题解 | #二叉排序树#

#include <stdio.h>
#include<stdlib.h>
typedef struct tree{
    int value;
    struct tree*lnode;
    struct tree*rnode;
}tree,*root ;
void insert(root t,int e){
    tree* temp=(root)malloc(sizeof(tree));
    temp->value=e;
    temp->lnode=NULL;
    temp->rnode=NULL;
    tree *a1=t,*a2=t;int tag=0;
    while(1){
        if(a1==NULL){
            if(tag==0){
                a2->lnode=temp;
            }else{
                a2->rnode=temp;
            }break;
        }else if(a1->value<e){
            a2=a1;a1=a1->rnode;tag=1;
        }else if(a1->value>e){
            a2=a1;a1=a1->lnode;tag=0;
        }else if(a1->value==e){
            free(temp);
            break;
        }
    }
}
void preorder(root t){
    if(t==NULL)return;
    printf("%d ",t->value);
    preorder(t->lnode);
    preorder(t->rnode);
}
void midorder(root t){
    if(t==NULL)return;
    midorder(t->lnode);
    printf("%d ",t->value);
    midorder(t->rnode);
}
void postorder(root t){
    if(t==NULL)return;
    postorder(t->lnode);
    postorder(t->rnode);
    printf("%d ",t->value);
}
int main() {
    int n;
    while(scanf("%d", &n)!=EOF){
    int e;
    scanf("%d",&e);
    tree* T=(root)malloc(sizeof(tree));
    T->value=e;
    T->lnode=NULL;
    T->rnode=NULL;
    for(int i=1;i<n;i++){
        int temp;
        scanf("%d",&temp);
        insert(T,temp);
    }
    preorder(T);
    printf("\n");
    midorder(T);
    printf("\n");
    postorder(T);
    printf("\n");
    }
    return 0;
}