From 2d48a86f5ee2d3cab8d0f4e8b2dbb101ff9f8125 Mon Sep 17 00:00:00 2001
From: Vincent Batts <vbatts@thisco.de>
Date: Sun, 13 Apr 2014 10:33:41 -0400
Subject: [PATCH] something like a huffman trie

---
 huffman.go | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/huffman.go b/huffman.go
index 38c0bea..c38b290 100644
--- a/huffman.go
+++ b/huffman.go
@@ -16,16 +16,22 @@ func (n Node) Lookup(value interface{}) *Node {
 }
 
 func NewPathTree(paths []string) *Node {
-	nodes := []Node{}
+	nodes := []*Node{}
 	for i := range paths {
-		node := Node{Weight: int64(i + 1), Value: paths[i]}
-		nodes = append(nodes, node)
+		nodes = append(nodes, &Node{Weight: int64(i + 1), Value: paths[i]})
 	}
 
-	nodeHeap := nodeInterface(nodes)
-	heap.Init(nodeHeap)
-
-	return &Node{}
+	h := nodeInterface(nodes)
+	h_ptr := &h
+	heap.Init(h_ptr)
+	count := h_ptr.Len()
+	for count > 1 {
+		left := heap.Pop(h_ptr)
+		right := heap.Pop(h_ptr)
+		heap.Push(h_ptr, Combine(left.(*Node), right.(*Node)))
+		count = h_ptr.Len()
+	}
+	return heap.Pop(h_ptr).(*Node)
 }
 
 func Combine(left *Node, right *Node) *Node {
@@ -43,10 +49,17 @@ func Combine(left *Node, right *Node) *Node {
 	}
 }
 
-type nodeInterface []Node
+type nodeInterface []*Node
 
-func (ni nodeInterface) Push(x interface{}) {}
-func (ni nodeInterface) Pop() interface{}   { return Node{} }
-func (ni nodeInterface) Len() int           { return len(ni) }
-func (ni nodeInterface) Less(i, j int) bool { return ni[i].Weight < ni[j].Weight }
-func (ni nodeInterface) Swap(i, j int)      { ni[i], ni[j] = ni[j], ni[i] }
+func (ni nodeInterface) Len() int            { return len(ni) }
+func (ni nodeInterface) Less(i, j int) bool  { return ni[i].Weight < ni[j].Weight }
+func (ni nodeInterface) Swap(i, j int)       { ni[i], ni[j] = ni[j], ni[i] }
+func (ni *nodeInterface) Push(x interface{}) { *ni = append(*ni, x.(*Node)) }
+func (ni *nodeInterface) Pop() interface{} {
+	old := *ni
+	n := len(old)
+	x := old[n-1]
+	*ni = old[0 : n-1]
+	return x
+
+}