BJFUOJ-265

基于二叉链表的二叉树的双序遍历

#include<iostream>
using namespace std;

typedef struct TreeNode {
	char val;
	TreeNode* left;
	TreeNode* right;
	TreeNode() :val('0'), left(nullptr), right(nullptr) {

	}
	TreeNode(char x) :val(x), left(nullptr), right(nullptr) {

	}
}TreeNode,*BiTree;

BiTree PreInsert() {

	char x;
	cin >> x;
	if (x == '0') return nullptr;
	TreeNode* root = new TreeNode(x);
	root->left = PreInsert();
	root->right = PreInsert();
	return root;
}

void TwoOrder(BiTree T) {
	if (T == nullptr) return;
	cout << T->val;
	TwoOrder(T->left);
	cout << T->val;
	TwoOrder(T->right);
}

int main() {

	BiTree T;
	while (true) {
		T = PreInsert();
		if (T == nullptr) break;
		TwoOrder(T);
		cout << endl;
	}
	

	return 0;
}