add count complete tree

Author: tg123

count-complete-tree-nodes/README.md

@@ -0,0 +1,70 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+public class Solution {
+    
+    int height(TreeNode root){
+        if(root == null) return 0;
+        
+        return 1 + height(root.left);
+    }
+    
+    
+    int leaves = 0;
+    boolean stop = false;
+    
+    void countLeaves(TreeNode root, int heightToLeaf){
+        
+        if(root == null) return;
+        
+        if(stop) return;
+        
+        if(heightToLeaf == 2) {
+
+            if(root.right != null){
+                leaves += 2;
+            } else {
+                
+                // at lease one is null
+                stop = true;
+                
+                if(root.left  != null) { 
+                    leaves += 1;
+                }
+            }
+            
+            
+            return;
+        }
+        
+        countLeaves(root.left,  heightToLeaf - 1);
+        countLeaves(root.right, heightToLeaf - 1);
+    }
+    
+    int perfectTreeNodeCount(int height){
+        if(height == 0) return 0;
+        if(height == 1) return 1;
+        
+        return (int)Math.pow(2, height) - 1;
+    }
+    
+    public int countNodes(TreeNode root) {
+        
+        int h = height(root);
+
+        countLeaves(root, h);
+        
+        if(!stop){
+            // perfect tree
+            return perfectTreeNodeCount(h);
+        }
+        
+        return perfectTreeNodeCount(h - 1) + leaves;
+    }
+}

count-complete-tree-nodes/Solution.java

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+---
+layout: solution
+title: Count Complete Tree Nodes
+date: 2015-06-08 00:30:07+08:00
+leetcode_id: 222
+---
+{% include_relative README.md %}