fix the logic of merkle tree

blockchain/merkle_tree.go

@@ -18,29 +18,29 @@ 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])
-	}
+	var nodes []*MerkleNode
 
 	for _, datum := range data {
 		node := NewMerkleNode(nil, nil, datum)
-		nodes = append(nodes, *node)
+		nodes = append(nodes, node)
 	}
 
-	for i := 0; i < len(data)/2; i++ {
-		var newLevel []MerkleNode
+	for len(nodes) > 1 {
+		var newLevel []*MerkleNode
+
+		if len(nodes)%2 != 0 {
+			nodes = append(nodes, nodes[len(nodes)-1])
+		}
 
 		for j := 0; j < len(nodes); j += 2 {
-			node := NewMerkleNode(&nodes[j], &nodes[j+1], nil)
-			newLevel = append(newLevel, *node)
+			node := NewMerkleNode(nodes[j], nodes[j+1], nil)
+			newLevel = append(newLevel, node)
 		}
 
 		nodes = newLevel
 	}
 
-	mTree := MerkleTree{&nodes[0]}
+	mTree := MerkleTree{nodes[0]}
 
 	return &mTree
 }