复制二叉树（非递归实现）

pbinary_tree_node copy_binary_tree(pbinary_tree_node bt){//先序遍历输出一颗树的全部结点值1,2,3stack<pbinary_tree_node> stack_left,stack_right;pbinary_tree_node newbt;if (bt!=NULL){//new rootnewbt=new binary_tree_node;newbt->data=bt->data;//travel bt and travel newbt at the same timestack_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;}

这个算法使用了两个栈，一个栈用来遍历原来的二叉树，另一个栈一边创建新的二叉树，一边同第一个栈同步，保存遍历时的轨迹。