leetcode 94. Binary Tree Inorder Traversal

原题：

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

For example:
Given binary tree [1,null,2,3],

   1
    \
     2
    /
   3

return [1,3,2].

Note: Recursive solution is trivial, could you do it iteratively?

代码如下：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
/**
 * Return an array of size *returnSize.
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* inorderTraversal(struct TreeNode* root, int* returnSize) {
    void A(struct TreeNode* root, int* returnSize,int* arrays);
    int* arrays;
    arrays=(int*)malloc(sizeof(int)*10000);
    A(root,returnSize,arrays);
    return arrays;
}
void A(struct TreeNode* root, int* returnSize,int* arrays)
{
    if(root==NULL)
        return ;
    A(root->left,returnSize,arrays);
    *(arrays+*returnSize)=root->val;
    (*returnSize)++;
    A(root->right,returnSize,arrays);
}

就是中序遍历的简单算法而已，没有啥太多可说的。