二叉树建树笔记

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


struct TreeNode;
typedef struct TreeNode * Position;
typedef struct TreeNode * SearchTree;

struct TreeNode{
    int element;
    SearchTree left;
    SearchTree right;
};

SearchTree MakeEmpty(SearchTree T) {
    if(T != NULL) {
        MakeEmpty(T->left);
        MakeEmpty(T->right);
        free(T);
    }
    return NULL;
}

SearchTree Insert(int element,SearchTree T) {
    if(T == NULL) {
        T = (SearchTree)malloc(sizeof(struct TreeNode));
        if(T == NULL) {
            printf("Out of Space");
        } else {
            T->element = element;
            T->left = T->right = NULL;
        }
    } else {
        if(element < T->element) {
            T->left = Insert(element,T->left);
        } else if(element > T->element) {
            T->right = Insert(element,T->right);
        }
    }
    return T;
}

void showAllTreeNode(SearchTree T) {

    if(T->left != NULL) {
        showAllTreeNode(T->left);
    }
    printf("element = %d\n",T->element);
    if(T->right != NULL) {
        showAllTreeNode(T->right);
    }
}


int main() {
    SearchTree head = NULL;
    int a[10] = {0,3,8,9,2,1,4,7,6,5};
    for( int i=0; i<10; i++) {
        head = Insert(a[i],head);
    }
    showAllTreeNode(head);

}