void find(struct TreeNode* root, int* returnSize ,int* result)
{
    if(root->left) find(root->left,returnSize,result);
    result[(*returnSize)++]=root->val;
    if(root->right) find(root->right,returnSize,result);
}
int* inorderTraversal(struct TreeNode* root, int* returnSize ) {
    if(!root) return NULL;
    int* result=malloc(sizeof(int)*1000);
    *returnSize=0;
    find(root,returnSize,result);
    return result;
}