C language-dynamically create a binary tree
What is a tree? A tree is a data structure. Common data structures are divided into hash, linear, tree, and graph. The binary tree is a typical representative of the tree data structure. Why is it special? Because it has at most two branches, it has 5 basic types, which are divided into empty binary trees, binary trees without leaf nodes, binary trees containing only the left subtree, binary trees containing only the right subtree, and binary trees with two branches. When these basic types are combined, they form a huge binary tree.
Well, the binary tree is introduced first, and the code is directly introduced below:
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include<stdlib.h>
#include<assert.h>
#include<windows.h>
typedef struct BinaryTree{
int data;
struct BinaryTree *left, *right;
}BT;
BT *CreatBT(int *num,int n){
assert(num!=NULL);
BT *r=NULL, *p;
BT *q, *qa;//两指针联动,qa永远在q的双亲结点
for (int i = 0; i < n;++i){
p = (BT*)malloc(sizeof(BT));
p->data = num[i];
p->left = NULL;
p->right = NULL;
if (!r){
r = p;
}
else{
q =qa= r;
while (q){
qa = q;
if (p->data>q->data){
q = q->right;
}
else{
q = q->left;
}
}
if (qa->data>p->data){
qa->left = p;
}
else{
qa->right = p;
}
}
}
return r;
}
void Show(BT *r){
//前序遍历二叉树
if (!r){
return;
}
printf("%d->",r->data);
Show(r->left);
Show(r->right);
}
int main(void){
int n;
printf("请输入数据长度：");
scanf("%d",&n);
int *num;
num = (int *)malloc(n*sizeof(int));
printf("请输入数据：");
for (int i = 0; i < n;++i){
scanf("%d",num+i);
}
Show(CreatBT(num, n));
free(num);
num = NULL;
system("pause");
return 0;
}
Preorder traversal of the binary tree: first visit the parent node, then the left child node, then the right child node, and the left child node may be a binary subtree, and the right child node may also be a binary subtree. So we need to use recursive thinking to complete the preorder traversal.