二叉树的四种遍历实现

二叉树的四种遍历实现

#include<iostream>
#include<queue>
using namespace std;

typedef struct BTNode
{
    int data;
    struct BTNode *lchild,*rchild;
}BTNode,*BTree;//二叉树节点
queue<BTree> q;//声明队列

void Create_Tree(BTree *T)//先序创建二叉树，0表示该子树为空树
{
    int cd;
    cin>>cd;

    if(0==cd) *T=NULL;
    else
    {
        *T=new BTNode;
        (*T)->data=cd;
        Create_Tree(&(*T)->lchild);
        Create_Tree(&(*T)->rchild);
    }

}

void DLR(BTree T)//先序遍历
{
    if(T!=NULL)
    {
        cout<<T->data<<" ";
        DLR(T->lchild);
        DLR(T->rchild);
    }
}

void LDR(BTree T)//中序遍历
{
    if(T!=NULL)
    {
        LDR(T->lchild);
        cout<<T->data<<" ";
        LDR(T->rchild);
    }
}

void LRD(BTree T)//后序遍历
{
    if(T!=NULL) 
    {   
        LRD(T->lchild);
        LRD(T->rchild);
        cout<<T->data<<" ";
    }
}

void LevelOrderTraverse(BTree T)//层序遍历
{
    cout<<T->data<<" ";
    if(T->lchild) q.push(T->lchild);
    if(T->rchild) q.push(T->rchild);
    q.pop();
    if(!q.empty()) LevelOrderTraverse(q.front());

}

int main()
{
    BTree T;
    cout<<"先序创建二叉树：";
    Create_Tree(&T);

    cout<<"前序遍历：";
    DLR(T);
    cout<<endl;

    cout<<"中序遍历：";
    LDR(T);
    cout<<endl;

    cout<<"后序遍历：";
    LRD(T);
    cout<<endl;

    cout<<"层序遍历：";
    q.push (T);
    LevelOrderTraverse(q.front());
    cout<<endl;

    return 0;
}

程序运行图：