Leetcode

Binary Tree Pruning

May 26, 2022 by aAshish

  • Time:O(n)
  • Space:O(h)

C++

 
class Solution {
 public:
  TreeNode* pruneTree(TreeNode* root) {
    if (!root)
      return nullptr;
    root->left = pruneTree(root->left);
    root->right = pruneTree(root->right);
    if (!root->left && !root->right && !root->val)
      return nullptr;
    return root;
  }
};

JAVA

 
class Solution {
  public TreeNode pruneTree(TreeNode root) {
    if (root == null)
      return null;
    root.left = pruneTree(root.left);
    root.right = pruneTree(root.right);
    if (root.left == null && root.right == null && root.val == 0)
      return null;
    return root;
  }
}

Python

 
class Solution:
  def pruneTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
    if not root:
      return None
    root.left = self.pruneTree(root.left)
    root.right = self.pruneTree(root.right)
    if not root.left and not root.right and not root.val:
      return None
    return root