用递归方法对二叉树进行先序、中序和后序遍历

二叉树为：

1

2 3

4 5 6 7

程序如下：

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#include<iostream>

#define N 7

using namespace std;

typedef struct node

{

struct node *leftChild;

struct node *rightChild;

int data;

}BiTreeNode, *BiTree;

BiTreeNode *createNode(int i)

{

BiTreeNode * q = new BiTreeNode;

q->leftChild = NULL;

q->rightChild = NULL;

q->data = i;

return q;

}

BiTree createBiTree()

{

BiTreeNode *p
= {NULL};

int i;

for(i = 0; i < N; i++)

p[i] = createNode(i + 1);

for(i = 0; i < N/2; i++)

{

p[i]->leftChild = p[i * 2 + 1];

p[i]->rightChild = p[i * 2 + 2];

}

return p[0];

}

int visit(BiTree T)

{

return T->data;

}

// 先序遍历

void preOrderTraverse(BiTree T)

{

if(T)

{

cout << visit(T) << " ";

preOrderTraverse(T->leftChild);

preOrderTraverse(T->rightChild);

}

}

// 中序遍历

void inOrderTraverse(BiTree T)

{

if(T)

{

inOrderTraverse(T->leftChild);

cout << visit(T) << " ";

inOrderTraverse(T->rightChild);

}

}

// 后序遍历

void postOrderTraverse(BiTree T)

{

if(T)

{

postOrderTraverse(T->leftChild);

postOrderTraverse(T->rightChild);

cout << visit(T) << " ";

}

}

int main()

{

BiTree T = createBiTree();

cout << "先序遍历:" << endl;

preOrderTraverse(T);

cout << endl << endl;

cout << "中序遍历:" << endl;

inOrderTraverse(T);

cout << endl << endl;

cout << "后序遍历:" << endl;

postOrderTraverse(T);

cout << endl << endl;

return 0;

}

结果为：

先序遍历:

1 2 4 5 3 6 7

中序遍历:

4 2 5 1 6 3 7

后序遍历:

4 5 2 6 7 3 1