/**
knakul853
 */
class Solution {
public:
    TreeNode* deleteNode(TreeNode* root, int key) {

        if( !root ) return NULL;


           if(root->val > key){
              root->left =  deleteNode(root->left, key);
               return root;
           }
          else  if(root->val < key){
              root->right =  deleteNode(root->right, key);
              return root;
           }

        else
        {

            auto node = findLeft(root->right);
            if(node ==NULL) return root->left;
            node->left = root->left;
            return root->right;
        }

        return root;

    }

    TreeNode* findLeft(TreeNode* root)
    {
        while(root != NULL &&root->left != NULL )root=root->left;

        return root;


    }
};