BFS in binary tree

Question

I\'m trying to write the codes for breadth-first search in binary tree. I\'ve stored all the data in a queue, but I can\'t figure out how to travel to all nodes and consume all

Answer 1

A BFS can be easily written without recursion. Just use a queue to order your expansions:

void BFS(btree *start)
{
    std::deque q;
    q.push_back(start);
    while (q.size() != 0)
    {
        btree *next = q.front();
        // you may want to print the current node here or do other processing
        q.pop_front();
        if (next->left)
            q.push_back(next->left);
        if (next->right)
            q.push_back(next->right);
    }
}

The key is that you don't need to traverse the tree recursively; you just let your data structure handle the order in which you visit nodes.

Note that I'm using the C++ deque here, but anything that lets you put items on the back and get them from the front will work fine.