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C语言实现二叉树遍历的迭代算法

2014-09-17 11:59 976 查看

本文实例讲述了C语言实现二叉树遍历的迭代算法，是数据结构算法中非常经典的一类算法。分享给大家供大家参考。

具体实现方法如下：

二叉树中序遍历的迭代算法：

#include <iostream>
#include <stack>
using namespace std;
struct Node {
Node(int i, Node* l = NULL, Node* r = NULL) : item(i), left(l), right(r) {}
int item;
Node* left;
Node* right;
};
Node* construct() {
Node* node6 = new Node(16);
Node* node5 = new Node(12);
Node* node4 = new Node(8);
Node* node3 = new Node(4);
Node* node2 = new Node(14, node5, node6);
Node* node1 = new Node(6, node3, node4);
Node* node0 = new Node(10, node1, node2);
return node0;
}
//递归算法
void inorder(Node *root)
{
if (root == NULL)
return;
inorder(root->left);
cout << root->item << " ";
inorder(root->right);
}
void preorder(Node *root)
{
if(root == NULL)
return;
cout << root->item << " ";
preorder(root->left);
preorder(root->right);
}
void postorder(Node *root)
{
if (root == NULL)
return;
postorder(root->left);
postorder(root->right);
cout << root->item << " ";
}
void postorder2(Node *root)
{
if (root == NULL)
return;
stack<Node *> nstack;
Node *pre = NULL;
nstack.push(root);
Node *node = NULL;
while (!nstack.empty())
{
node = nstack.top();
if (pre != node->left && pre != node->right)
{
if (node->right)
nstack.push(node->right);
if (node->left)
nstack.push(node->left);
}
if (node->left == NULL && node->right == NULL
|| pre == node->left || pre == node->right)
{
cout << node->item << " ";
nstack.pop();
}
pre = node;
}
}
void preorder2(Node *root)
{
if(root == NULL)
return;
stack<Node *> nstack;
Node *node = root;
while (node != NULL || !nstack.empty())
{
while(node != NULL)
{
cout << node->item << " ";
nstack.push(node);
node = node->left;
}
node = nstack.top();
nstack.pop();
node = node->right;
}
}
void preorder3(Node *root)
{
if (root == NULL)
return;
stack<Node *> nstack;
nstack.push(root);
Node *node = NULL;
while (!nstack.empty())
{
node = nstack.top();
nstack.pop();
cout << node->item << " ";
if (node->right)
nstack.push(node->right);
if (node->left)
nstack.push(node->left);
}
}
//迭代算法
void inorder2(Node *root)
{
if(root == NULL)
return;
stack<Node *> nstack;
nstack.push(root);
Node *next = root->left;
while (next != NULL || !nstack.empty())
{
while (next != NULL)
{
nstack.push(next);
next = next->left;
}
next = nstack.top();
nstack.pop();
cout << next->item << " ";
next = next->right;
}
}
int main()
{
Node *root = construct();
cout << "---------中序遍历递归---------" << endl;
inorder(root);
cout << endl;
cout << "---------中序遍历迭代---------" << endl;
inorder2(root);
cout << endl;
cout << "---------先序遍历递归---------" << endl;
preorder(root);
cout << endl;
cout << "---------先序遍历迭代1---------" << endl;
preorder2(root);
cout << endl;
cout << "---------先序遍历迭代2---------" << endl;
preorder3(root);
cout << endl;
cout << "---------后序遍历递归---------" << endl;
postorder(root);
cout << endl;
cout << "---------后序遍历迭代---------" << endl;
postorder2(root);
}

关于前序遍历，后来又写的算法如下，供大家参考：

void preOrderIterator(Node *root)
{
if (root == NULL)
return;
stack<Node*> nstack;
nstack.push(root);
while (!nstack.empty())
{
Node *top = nstack.top();
while (top != NULL)
{
if (top->left)
nstack.push(top->left);
cout << top->data << " ";
top = top->left;
}
while (top == NULL && !nstack.empty())
{
top = nstack.top()->right;
nstack.pop();
}
if (top != NULL)
nstack.push(top);
}
}

相信本文所述对大家C程序算法设计的学习有一定的借鉴价值。

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标签： C语言二叉树

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