给定一个二叉树,返回它的中序 遍历。
示例:
输入: [null,1,3,2,null]
1
\
2
/
3
输出: [1,3,2]
https://leetcode-cn.com/problems/binary-tree-inorder-traversal/description/
递归访问
/**
* 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 TreeNodeSize(struct TreeNode* root)
{
if(NULL == root)
return 0;
return 1 + TreeNodeSize(root->left) + TreeNodeSize(root->right);
}
void _inorderTraversal(struct TreeNode *root,int *array,int *pIndex)
{
if(NULL == root)
return ;
_inorderTraversal(root->left,array,pIndex);
array[*pIndex]=root->val;
(*pIndex)++;
_inorderTraversal(root->right,array,pIndex);
}
int* inorderTraversal(struct TreeNode* root, int* returnSize) {
*returnSize = TreeNodeSize(root);
int *array = (int *)malloc(*returnSize * sizeof(*returnSize));
int index = 0;
_inorderTraversal(root,array,&index);
return array;
}