8.8 Leetcode 222 Count complete Tree Nodes

Question:

Count Complete Tree NodesTotal accepted:11040 Total submissions:53992my submissions QuestionSolution

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.

Analysis:

Steps to solve this problem:
1) Get the height of Left-most part
2) Get the height of Right-most part
3) When they is equal, the # of nodes = 2^h-1
4) when they is not equal, recursively get # of nodes from Left&right sub-trees

 Public intCountnodes (TreeNode root) {//Notice The traditional traversal would exceed the time limit and we also can ' t use Math.pow () cause it is too slow.        if(Root = =NULL)return0; TreeNode LN= root, RN =Root; intL = 0, r = 0;  while(LN! =NULL) {L++; ln=Ln.left; }         while(rn! =NULL) {R++; RN=Rn.right; }//Math.pow (2,n) = 2<< (n-1) e.g. 2^1 = = 2 = 2<<0        if(L = = r)return(2<< (L-1))-1;//notice "<<" is right connect so we need "() out of 2<< (L-1)"        return1 + countnodes (root.left) +countnodes (root.right); }  

8.8 Leetcode 222 Count complete Tree Nodes