运用栈非递归遍历二叉树

最新推荐文章于 2024-02-26 17:53:30 发布

原创最新推荐文章于 2024-02-26 17:53:30 发布 · 425 阅读

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1.先序遍历一颗二叉树
方法一：

void preTree1(TreeNode* root)
{
    if(!root)
        return ;
    stack<TreeNode*>treestack;
    cout<<root->data<<' ';
    treestack.push(root);

    while(treestack.size())
    {
        TreeNode* node=treestack.top();
        if(node->left)
        {
            cout<<node->left->data<<' ';
            treestack.push(node->left);
            node->left=NULL;
        }
        else
        {

            treestack.pop();
            if(node->right)
            {
                cout<<node->right->data<<' ';
                treestack.push(node->right);
            }
        }
    }
}

方法二：

void preTree2(TreeNode* root)
{
    if(!root)
        return;
    stack<TreeNode*>treestack;
    treestack.push(root);
    while(treestack.empty()==false)
    {
        TreeNode* node=treestack.top();
        cout<<node->data<<' ';
        treestack.pop();
        if(node->right)
            treestack.push(node->right);
        if(node->left)
            treestack.push(node->left);
    }
}

2.中序遍历二叉树

方法一：


void inTree1(TreeNode* root)
{
    if(!root)
        return;
    stack<TreeNode*>treestack;
    treestack.push(root);
    while(treestack.size())
    {
        TreeNode* node=treestack.top();
        if(node->left)
        {
            treestack.push(node->left);
            node->left=NULL;
        }
        else
        {
            treestack.pop();
            cout<<node->data<<' ';
            if(node->right)
            {
                treestack.push(node->right);            
            }
        }
    }
}

方法二：


TreeNode*  inTree2(TreeNode* node)
{
    TreeNode* root=node;
    if(!root)
        return NULL;
    stack<TreeNode*>treestack;

    while(treestack.size()||root)
    {
        while(root)
        {
            treestack.push(root);
            root=root->left;
        }   
        if(treestack.size())
        {
            root=treestack.top();
            treestack.pop();
            cout<<root->data<<' ';
            root=root->right;
        }
    }
    return node;
}

3.后序遍历二叉树

void lastTree(TreeNode* root)
{
    if(!root)
        return;
    stack<TreeNode*>treestack;
    treestack.push(root);
    while(treestack.size())
    {
        TreeNode* node=treestack.top();
        if(node->left)
        {
            treestack.push(node->left);
            node->left=NULL;
        }
        else if(node->right)
        {
                treestack.push(node->right);
                node->right=NULL;
        }
        else
        {
            cout<<node->data<<' ';
            treestack.pop();
        }
    }
}

4.层序遍历二叉树


void lay(TreeNode* root)
{
    if(!root)
        return;
    deque<TreeNode*>treedeque;
    treedeque.push_back(root);
    while(treedeque.size())
    {
        TreeNode* node=treedeque.front();
        treedeque.pop_front();
        cout<<node->data<<' ';
        if(node->left)
            treedeque.push_back(node->left);
        if(node->right)
            treedeque.push_back(node->right);

    }
}