Leetcode_94_binary Tree inorder Traversal

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94 Binary Tree Inorder Traversal


Given a binary tree, return the inorder traversal of its nodes ' values.


For example:
Given binary Tree {1,#,2,3},
1
\
2
/
3
return [1,3,2].


Note:recursive solution is trivial, could do it iteratively?

Method One: Stack/** * Definition for binary tree * struct TreeNode {*     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode (int x): Val (x), left (null), right (NULL) {} *}; */class Solution {public:    vector<int> inordertraversal (TreeNode *root) {        vector<int> ans;        Ans.clear ();        if (root==null)            return ans;        Stack<treenode *> St;        TreeNode *p = root;        while (P!=null | |!st.empty ())        {            while (p!=null)            {                st.push (p);                p = p->left;            }            if (!st.empty ())            {                p = st.top ();                St.pop ();                Ans.push_back (p->val);                p = p->right;            }        }        return ans;    };

Method Two: Recursive class solution {vector<int> ans;public:    void Inordertraversalutil (TreeNode *root)    {        if ( Root==null)            return;        Inordertraversalutil (root->left);        Ans.push_back (root->val);        Inordertraversalutil (root->right);    }        Vector<int> inordertraversal (TreeNode *root) {        ans.clear ();        if (root = NULL)            return ans;        Inordertraversalutil (root);        return ans;    };

Leetcode_94_binary Tree inorder Traversal