数据结构练习（11）从上往下遍历二元树

http://zhedahht.blog.163.com/blog/static/2541117420072199173643/

数的广度优先遍历，队列，没啥好说的。

#include <deque>

struct btree {
    int m_value;
    btree *m_left;
    btree *m_right;
};

void print_tree(btree *root)
{
    if (root == NULL)
        return root;

    std::deque<btree*> deq;
    deq.push_back(root);

    while (deq.size())
    {
        btree *node = deq.front();
        deq.pop_front();

        cout << node->m_value << ' ';

        if (node->m_left)
            deq.push_back(node->m_left);
        if (node->m_right)
            deq.push_back(node->m_right);   
    }
}