【leetcode】两数之和 IV

int n;
void func(struct TreeNode* root,int* arr)
{
    if (!root)return;
    arr[n++] = root->val;
    func(root->left,arr);
    func(root->right,arr);
}
bool findTarget(struct TreeNode* root, int k){
    if (!root)return false;
    int arr[10000] = {0};
    n = 0;
    arr[n++] = root->val;
    func(root->left,arr);
    func(root->right,arr);
    for (int i=0; i<n-1; i++)
    {
        for (int j=i+1; j<n; j++)
        {
            if (arr[i] + arr[j] == k)
            {
                return true;
            }
        }
    }
    return false;
}