[数据结构与算法]二叉树的前、中、后序 实现

//2xTree.h
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>

struct node {
	char data;
	struct node* left;
	struct node* right;
};

typedef struct node node;

//前序：根->左子树->右子树
void prevOrder(node* n);

//中序：左子树->根->右子树
void midOrder(node* n);

//后序：左子树->右子树->根
void lastOrder(node* n);

//2xTree.c
#include"2xTree.h"

//前序：根->左子树->右子树
void prevOrder(node* root) {
	if (root == NULL)
	{
		return NULL;
	}
	printf("%c", root->data);
	prevOrder(root->left);
	prevOrder(root->right);
}

//中序：左子树->根->右子树
void midOrder(node* root) {
	if (root == NULL)
	{
		return NULL;
	}
	midOrder(root->left);
	printf("%c", root->data);
	midOrder(root->right);
}

//后序：左子树->右子树->根
void lastOrder(node* root) {
	if (root == NULL)
	{
		return NULL;
	}
	lastOrder(root->left);
	lastOrder(root->right);
	printf("%c", root->data);

}

//main.c
#include"2xTree.h"

void main() {
	//初始化一个二叉树
	node* A = (node*)malloc(sizeof(node));
	A->data = 'A';
	A->left = NULL;
	A->right = NULL;
	node* B = (node*)malloc(sizeof(node));
	B->data = 'B';
	B->left = NULL;
	B->right = NULL;
	node* C = (node*)malloc(sizeof(node));
	C->data = 'C';
	C->left = NULL;
	C->right = NULL;
	node* D = (node*)malloc(sizeof(node));
	D->data = 'D';
	D->left = NULL;
	D->right = NULL;
	node* E = (node*)malloc(sizeof(node));
	E->data = 'E';
	E->left = NULL;
	E->right = NULL;
	
	A->left = B;
	A->right = C;
	B->left = D;
	B->right = E;
	printf("前序：");
	prevOrder(A);
	printf("\n");
	printf("中序：");
	midOrder(A);
	printf("\n");
	printf("后序：");
	lastOrder(A);

}

程序运行结果：