后序遍历的非递归实现

如题

思路：先介绍先序遍历的非递归实现，首先根节点入栈，根节点出栈的时候再把它的右左孩子入栈，再把栈顶（也就是左孩子）出栈，把栈顶元素的右左孩子入栈，此过程一直执行，直到栈为空，出栈的顺序就是先序遍历。
先序遍历是在节点出栈时入栈右左孩子。对于后序遍历，不应该在父节点出栈时，才把右左孩子入栈，应该在入栈时就把右左孩子一并入栈。在父节点入栈时，应判断右左孩子是否入过栈，设一个标记负责记录。

typedef struct stackTreeNode
{
  �BTree treenode;
  int flag;
}* FTree;

int PostOrder(BTree root)
{
  stack<FTree> stackTree;
  FTree tree = (FTree) malloc(sizeof(struct stackTreeNode));
  tree->treenode = root;
  tree->flag = 0;
  stackTree.push(tree);
  
while(!stacktree)
{
  FTree temp_tree = stackTree.pop()
  if(temp_tree.flag == 1)
  {
    cout<<temp_tree->treenode->data<<' ';
    stackTree.pop();
  }
else
{
  if(temp_tree->treenode->rchild)
  {
    FTree sTree = (FTree)malloc(sizeof(struct stackTreeNode));
    sTree->treenode = temp_tree->treenode->rchild;
    sTree->flag = 0;
    stackTree.push(sTree);
  }
  temp_tree->flag++;
  if(temp_tree->treenode->lchild)
  {
    FTree sTree = (FTree) malloc(sizeof(struct stackTreeNode));
    sTree->treenode = temp_tree->treenode->lchild;
    sTree->flag = 0;
    stackTree.push(sTree);
  }
temp_tree->flag++;
}
}
return 1;
}