復制二叉樹（非遞歸實現）

復制二叉樹（非遞歸實現）:

pbinary_tree_node copy_binary_tree(pbinary_tree_node bt)
{//先序遍歷輸出一顆樹的全部結點值1,2,3
stack<pbinary_tree_node> stack_left,stack_right;
pbinary_tree_node newbt;
if (bt!=NULL)
{
//new root
newbt=new binary_tree_node;
newbt->data=bt->data;

//travel bt and travel newbt at the same time
stack_left.push(bt);
stack_right.push(newbt);

while (!stack_left.empty())
{
pbinary_tree_node pleft=stack_left.top();
pbinary_tree_node pright=stack_right.top();
stack_left.pop();
stack_right.pop();
if (pleft->rchild!=0)
{
stack_left.push(pleft->rchild);
pright->rchild=new binary_tree_node;
pright->rchild->data=pleft->rchild->data;
stack_right.push(pright->rchild);
}
if (pleft->lchild!=0)
{
stack_left.push(pleft->lchild);
pright->lchild=new binary_tree_node;
pright->lchild->data=pleft->lchild->data;
stack_right.push(pright->lchild);
}
}
}
return newbt;
}

這個算法使用了兩個棧，一個棧用來遍歷原來的二叉樹，另一個棧一邊創建新的二叉樹，一邊同第一個棧同步，保存遍歷時的軌跡。