From b3e0fa817562723f444bf0ad58b5c848e3d0c0e7 Mon Sep 17 00:00:00 2001
From: bboyjing <bboyjing@gmail.com>
Date: Thu, 19 Apr 2018 13:54:38 +0800
Subject: [PATCH] optimize NewMerkleTree

---
 merkle_tree.go | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/merkle_tree.go b/merkle_tree.go
index 7a4156bd..e0714178 100644
--- a/merkle_tree.go
+++ b/merkle_tree.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"crypto/sha256"
+	"log"
 )
 
 // MerkleTree represent a Merkle tree
@@ -19,29 +20,32 @@ type MerkleNode struct {
 // NewMerkleTree creates a new Merkle tree from a sequence of data
 func NewMerkleTree(data [][]byte) *MerkleTree {
 	var nodes []MerkleNode
-
-	if len(data)%2 != 0 {
-		data = append(data, data[len(data)-1])
-	}
-
+	
 	for _, datum := range data {
 		node := NewMerkleNode(nil, nil, datum)
 		nodes = append(nodes, *node)
 	}
-
-	for i := 0; i < len(data)/2; i++ {
+	
+	if len(nodes) == 0 {
+		log.Panic("No merkel nodes")
+	}
+	
+	for len(nodes) > 1 {
+		if len(nodes)%2 != 0 {
+			nodes = append(nodes, nodes[len(nodes)-1])
+		}
+		
 		var newLevel []MerkleNode
-
-		for j := 0; j < len(nodes); j += 2 {
-			node := NewMerkleNode(&nodes[j], &nodes[j+1], nil)
+		for i := 0; i < len(nodes); i += 2 {
+			node := NewMerkleNode(&nodes[i], &nodes[i+1], nil)
 			newLevel = append(newLevel, *node)
 		}
-
+		
 		nodes = newLevel
 	}
-
+	
 	mTree := MerkleTree{&nodes[0]}
-
+	
 	return &mTree
 }