# Count Complete Tree Nodes

Source: Internet
Author: User

Given a complete binary tree, count the number of nodes.

Definition of a complete binary tree from Wikipedia:
In a complete binary tree every level, except possibly the last, was completely filled, and all nodes As far left as possible. It can has between 1 and 2h nodes inclusive at the last level H.

`1 /**2 * Definition for a binary tree node.3 * public class TreeNode {4 * int val;5 * TreeNode left;6 * TreeNode right;7 * TreeNode (int x) {val = x;}8  * }9  */Ten  Public classSolution { One      Public intcountnodes (TreeNode root) { A      -         intLeftdepth =leftdepth (root); -         intRightdepth =rightdepth (root); the      -         if(Leftdepth = =rightdepth) { -             return(1<< leftdepth)-1; -         } +         return 1+ countnodes (root.left) +countnodes (root.right); -      +     } A      at     Private intrightdepth (TreeNode root) { -         intdepth =0; -          while(Root! =NULL) { -Root =Root.right; -depth++; -         } in         returndepth; -     } to      +     Private intleftdepth (TreeNode root) { -         intdepth =0; the          while(Root! =NULL) { *Root =Root.left; \$depth++;Panax Notoginseng         } -         returndepth; the     } +}`

Count Complete Tree Nodes

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