非递归求树的深度

非递归求深度有两种算法：1，现将算法改成先序遍历，在改写成非递归方式。先序遍历遍历是：遍历一个节点前，先算出当前节点在哪一层，层数最大就等于二叉树的深度。

typedef struct Node
{
  char data;
  struct Node* lchild;
  struct Node* rchild;
  struct Node* parent;
}BNode, *BTree;

int max(int a, int b)
{
  return a>b?a:b;
}
int getDepthPreorder(BTree root)
{
  struct Info
  {
    const BTree TreeNode;
    int level;
  };
  deque<Info> dq;
  int level = -1;
  int TreeHeight = -1;
  
  while(1)
  {
    while(root)
    {
      ++level;
      if(root->rchild)
      {
            Info info = {root->rchild, level};
            dq.push_back(info);
      }
      root = root->lchild;
    }
  TreeHeight = max(TreeHeight, level);
  if(dq.empty())
    break;
  const Info& info = dq.back();
  root = info.TreeNode;
  level = info.level;
  dq.pop_back();
  }
return TreeHeight;
}