题解 | #二叉树遍历#

#include<iostream>
using namespace std;

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

string str;
int pos = 0;//当前遍历到str的哪个节点 

//根据先序建立二叉树
//当树构建完成时,返回树的根节点 
TreeNode* BuildTree(){
	
	char c = str[pos++];//pos++不能忘
	
	if(c == '#'){
		return NULL;
	}else{
		TreeNode* root = new TreeNode;
		root->data = c;
		root->left = BuildTree();
		root->right = BuildTree();
		return root;//此子树建立完成,返回根节点	
	} 
	 
}

void InOrder(TreeNode* root){
	if(root == NULL) return;
	else{
		InOrder(root->left);
		cout<<root->data<<" ";
		InOrder(root->right);
	}
}

int main(){
	
	while(getline(cin,str)){
		TreeNode* root = BuildTree();
    	InOrder(root);
    	cout<<endl;	
	}
    
    return 0;
}