二叉树的层次遍历

      8

     / \

    6   10

   / \  / \ 

  5  7 9   11 

层次遍历输出结果： 8,6,10,5,7,9,11

#include <deque>

using std::deque;

#include <iostream>

using namespace std;

template<typename T>

struct TreeNode

{

public:

    TreeNode(T value);

    void setLeftChild( TreeNode *lChild );

    void setRightChild( TreeNode *rChild );

    TreeNode *getLeftChild ();

    TreeNode *getRightChild();

    void print();

private:

    TreeNode *mLchild;

    TreeNode *mRchild;

    T mValue;

};

template<typename T>

TreeNode<T>::TreeNode(T value):mValue(value),mLchild(0),mRchild(0)

{

}

template<typename T>

void TreeNode<T>::setLeftChild( TreeNode *lChild )

{

    mLchild = lChild;

}

template<typename T>

void TreeNode<T>::setRightChild( TreeNode *rChild )

{

    mRchild = rChild;

}

template<typename T>

TreeNode<T> *

TreeNode<T>::getLeftChild ( )

{

    return mLchild;

}

template<typename T>

TreeNode<T> *

TreeNode<T>::getRightChild ( )

{

    return mRchild;

}

template<typename T>

void

TreeNode<T>::print()

{

    cout << mValue <<endl;

}

template<typename T>

TreeNode<T> *

BuildTree()

{

    TreeNode<int> *r8 = new TreeNode<int> ( 8 );

    TreeNode<int> *r6 = new TreeNode<int> ( 6 );

    TreeNode<int> *r10 = new TreeNode<int> ( 10 );

    TreeNode<int> *r5 = new TreeNode<int> ( 5 );

    TreeNode<int> *r7 = new TreeNode<int> ( 7 );

    TreeNode<int> *r9 = new TreeNode<int> ( 9 );

    TreeNode<int> *r11 = new TreeNode<int> ( 11 );

    r8->setLeftChild(r6);

    r8->setRightChild(r10);

    r6->setLeftChild(r5);

    r6->setRightChild(r7);

    r10->setLeftChild(r9);

    r10->setRightChild(r11);

    return r8;

}

template<typename T>

void printTree(TreeNode<T> *node)

{

    deque<TreeNode<T>*> fifo;

    fifo.push_back(node);

    while ( fifo.size() )

    {

        TreeNode<T> *front = fifo.front();

        fifo.pop_front();

        front->print();

        if ( front->getLeftChild() )

        {

            fifo.push_back(front->getLeftChild());

        }

        if ( front->getRightChild() )

        {

            fifo.push_back(front->getRightChild());

        }

    }

}

int main()

{

    TreeNode<int> *node = BuildTree<int>();

    printTree(node);

    return 0;

}