0814-BinaryTreePruning.cs

//-----------------------------------------------------------------------------
// Runtime: 88ms
// Memory Usage: 24 MB
// Link: https://leetcode.com/submissions/detail/360503671/
//-----------------------------------------------------------------------------

namespace LeetCode
{
    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     public int val;
     *     public TreeNode left;
     *     public TreeNode right;
     *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
     *         this.val = val;
     *         this.left = left;
     *         this.right = right;
     *     }
     * }
     */
    public class _0814_BinaryTreePruning
    {
        public TreeNode PruneTree(TreeNode root)
        {
            if (root == null) return null;
            if (root.left == null && root.right == null && root.val == 0) 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;
        }
    }
}