题解 | #二叉树遍历#

按照先序建立二叉树即可，然后再按照中序输出。

#include<iostream>
using namespace std;
typedef struct node{
    char val;
    struct node *left,*right;
}*TreeNode,Node;
void build(TreeNode &root,string &str){
    char c = str[0];
    str = str.substr(1);
    if(c == '#')
        return;
    if(root == NULL){
        root = (TreeNode)malloc(sizeof(Node));
        root->val = c;
        root->left = NULL;
        root->right = NULL;
    }
    build(root->left,str);
    build(root->right,str);
}
void mid(TreeNode root){
    if(root == NULL)
        return;
    mid(root->left);
    cout << root->val << " ";
    mid(root->right);
}
int main()
{
    string str;
    while(cin >> str){
        TreeNode root = NULL;
        build(root,str);
        mid(root);
        cout << endl;
    }
}