Package g0201_0300.s0222_count_complete_tree_nodes

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    222 - Count Complete Tree Nodes\.

    Medium

    Given the root of a complete binary tree, return the number of the nodes in the tree.

    According to Wikipedia , every level, except possibly the last, is completely filled in a complete binary tree, and all nodes in the last level are as far left as possible. It can have between 1 and <code>2<sup>h</sup></code> nodes inclusive at the last level h.

    Design an algorithm that runs in less than O(n) time complexity.

    Example 1:

    Input: root = 1,2,3,4,5,6

    Output: 6

    Example 2:

    Input: root = []

    Output: 0

    Example 3:

    Input: root = 1

    Output: 1

    Constraints:

    • The number of nodes in the tree is in the range <code>0, 5 * 10<sup>4</sup></code>.

    • <code>0 <= Node.val <= 5 * 10<sup>4</sup></code>

    • The tree is guaranteed to be complete.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer countNodes(TreeNode root)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait