text: /**
   * Definition for a binary tree node.
   * struct TreeNode {
   *     int val;
   *     TreeNode *left;
   *     TreeNode *right;
   *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
   *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
   *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
   * };
   */
  class Solution {
  public:
      TreeNode* pruneTree(TreeNode* root) {
          if(root == NULL){
              return NULL;
          }
          
          TreeNode* leftChild = pruneTree(root->left);
          TreeNode* rightChild = pruneTree(root->right);
          
          root->left = leftChild;
          root->right = rightChild;
          
          if(leftChild == NULL && rightChild == NULL && root->val == 0){
              return NULL;
          }
          
          return root;
      }
  };