二叉树各种遍历方法（c++）

Posted 2021-06-06 牧空

二叉树的常规遍历有：先序遍历、中序遍历、后序遍历

struct TreeNode
{
    char data;
    TreeNode *left;
    TreeNode *right;
    TreeNode(char c) : data(c), left(NULL), right(NULL) {}
};
//先序遍历
void PreOrder(TreeNode *root)
{
    if (root == NULL)
        return;
    printf("%c ", root->data);//Visit()
    PreOrder(root->left);
    PreOrder(root->right);
    return;
}
//中序遍历
void InOrder(TreeNode *root)
{
    if (root == NULL)
        return;
    InOrder(root->left);
    printf("%c ", root->data);
    InOrder(root->right);
    return;
}
//后序遍历
void PostOrder(TreeNode *root)
{
    if (root == NULL)
        return;
    PostOrder(root->left);
    PostOrder(root->right);
    printf("%c ", root->data);
    return;
}

---

层次遍历

void LevelOrder(TreeNode *root)
{
    queue<TreeNode *> q;
    if (root == NULL)
        return;
    q.push(root);
    while (!q.empty())
    {
        TreeNode *node = q.front();
        q.pop();
        printf("%c ", node->data);//Visit()
        if (node->left != nullptr)
            q.push(node->left);
        if (node->right != nullptr)
            q.push(node->right);
    }
    return;
}