遍历二叉树总结

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/hf19931101/article/details/79478845

1.递归遍历

struct bnode
{
    char data;
    struct bnode *lchild,*rchild;
};
typedef bnode* bitre;

//递归先序遍历
void PreOrderRec(bitre root)
{
    cout << root->data;
    PreOrderRec(root->lchild);
    PreOrderRec(root->rchild);
}

//递归中序遍历
void InOrderRec(bitre root)
{
    PreOrderRec(root->lchild);
    cout << root->data;
    PreOrderRec(root->rchild);
}

//递归后序遍历
void InOrderRec(bitre root)
{
    PreOrderRec(root->lchild);
    PreOrderRec(root->rchild);
    cout << root->data;
}

2.非递归遍历

struct bnode
{
    char data;
    struct bnode *lchild,*rchild;
};
typedef bnode* bitre;

struct TreeNode
{
    bitre node;
    bool vis;

    TreeNode(bitre node, bool vis)
    {
        this->node = node;
        this->vis = vis;
    }
};

//先序遍历：根->左孩子->右孩子
void PreOrder(TreeNode root)
{
    stack<TreeNode> stk;
    stk.push(root);

    while (!stk.empty())
    {
        TreeNode curNode = stk.top();
        stk.pop();
        if (!curNode.node)
        {
            continue;
        }
        if (curNode.vis)
        {
            cout << curNode.node->data;
        }
        else
        {
            stk.push(TreeNode(curNode.node->rchild, false));
            stk.push(TreeNode(curNode.node->lchild, false));
            stk.push(TreeNode(curNode.node, true));
        }
    }
}

//中序遍历：左孩子->根->右孩子
void InOrder(TreeNode root)
{
    stack<TreeNode> stk;
    stk.push(root);

    while (!stk.empty())
    {
        TreeNode curNode = stk.top();
        stk.pop();
        if (!curNode.node)
        {
            continue;
        }
        if (curNode.vis)
        {
            cout << curNode.node->data;
        }
        else
        {
            stk.push(TreeNode(curNode.node->rchild, false));
            stk.push(TreeNode(curNode.node, true));
            stk.push(TreeNode(curNode.node->lchild, false));
        }
    }
}

//后序遍历: 左孩子->右孩子->根
void PostOrder(TreeNode root)
{
    stack<TreeNode> stk;
    stk.push(root);

    while (!stk.empty())
    {
        TreeNode curNode = stk.top();
        stk.pop();
        if (!curNode.node)
        {
            continue;
        }
        if (curNode.vis)
        {
            cout << curNode.node->data;
        }
        else
        {
            stk.push(TreeNode(curNode.node, true));
            stk.push(TreeNode(curNode.node->rchild, false));
            stk.push(TreeNode(curNode.node->lchild, false));
        }
    }
}