[二叉树建树] 根据前序遍历构造二叉树

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;

string input;

struct node
{
    char data;
    node * lchild,*rchild;
};

void preOrder(node * & root,int & index)
{
    if(index>=input.length())
    {
        return ;
    }
    if(input[index]==‘#‘)
    {
        root=NULL;
        index++;
    }
    else
    {
        root=new node;
        root->data=input[index];
        index++;
        preOrder(root->lchild,index);
        preOrder(root->rchild,index);
        
    }
}

void inOrder(node * root)
{
    if(root==NULL)
    {
        return ;
    }
    inOrder(root->lchild);
    cout<<root->data<<" ";
    inOrder(root->rchild);
}

int main()
{
    while(cin>>input)
    {
        node * root=NULL;
        int index=0;
        preOrder(root,index);
        inOrder(root);
        cout<<endl;
    }
}