中跟遍历__非递归操作

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// 先序(附带叶子标记)建树#include<iostream>#include<stdio.h>#include<stdlib.h>#include<string.h>#include<stack>#include<string>using namespace std;struct node{    char data;    node* lchild;    node* rchild;};void buildtree(char* str,node* root){    stack<node*> sta;    int pos = 0;    int len = strlen(str);    node* tmp;    root->data = str[pos++];    root->lchild = NULL;    root->rchild = NULL;    sta.push(root);    while(pos < len)    {          while(true)          {                  node* nl = new node;                  nl->data = str[pos];                  nl->lchild = NULL;                  nl->rchild = NULL;                  if(str[pos]=='*')                 {                        free(nl);                        break;                 }                  sta.top()->lchild = nl;                  sta.push(nl);                  ++pos;           }           tmp = sta.top();           sta.pop();           ++pos;           while(str[pos]=='*')           {                 if(!sta.empty())                 {                     tmp = sta.top();                     sta.pop();                 }                 ++pos;           }           if(pos >= len)            break;            node* nr = new node;            nr->data = str[pos];            nr->lchild = NULL;            nr->rchild = NULL;            sta.push(nr);            tmp->rchild = nr;            ++pos;    }    return;}void visit_rootsecond(node* root){      stack<node*> sta;      bool _end = false;      node* p;      sta.push(root);      while(!sta.empty())      {          p = sta.top();          while(p)          {               p = p->lchild;               sta.push(p);          }          sta.pop();          p = sta.top();          printf("%c",p->data);          p = p->rchild;          sta.pop();          if(p)          {              sta.push(p);              continue;          }          while(p==NULL)          {              if(sta.empty())              {                  _end = true;                  break;              }              p = sta.top();              sta.pop();              p = p->rchild;          }          if(!_end)          {              sta.push(p);          }      }}int main(){    char* str = new char[100];    gets(str);    //printf("%s",str);    node* root = new node;    buildtree(str,root);    return 0;}
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