From 2f2f4bff5fa2a10fe9ebf551af3d6e9434e1b928 Mon Sep 17 00:00:00 2001
From: Gianni Ceccarelli <gianni.ceccarelli@broadbean.com>
Date: Thu, 1 Aug 2019 12:03:11 +0100
Subject: go model

---
 go/mixed-server.go      | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
 go/mixed-server_test.go | 24 +++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 go/mixed-server.go
 create mode 100644 go/mixed-server_test.go

diff --git a/go/mixed-server.go b/go/mixed-server.go
new file mode 100644
index 0000000..44dfcdc
--- /dev/null
+++ b/go/mixed-server.go
@@ -0,0 +1,63 @@
+package main
+
+import (
+	"sort"
+	"sync"
+)
+
+type wordsByCount struct {
+	words *map[string]uint
+	keys  []string
+}
+
+func newWordsByCount(w *map[string]uint) wordsByCount {
+	keys := make([]string, len(*w))
+	i := 0
+	for w, _ := range *w {
+		keys[i] = w
+		i++
+	}
+
+	return wordsByCount{words: w, keys: keys}
+}
+func (wbc wordsByCount) Len() int { return len(*wbc.words) }
+func (wbc wordsByCount) Swap(i, j int) {
+	wbc.keys[i], wbc.keys[j] = wbc.keys[j], wbc.keys[i]
+}
+func (wbc wordsByCount) Less(i, j int) bool {
+	return (*wbc.words)[wbc.keys[i]] > (*wbc.words)[wbc.keys[j]]
+}
+func (wbc wordsByCount) MostCommonWords() []string {
+	sort.Sort(wbc)
+	mcw := make([]string, len(*wbc.words))
+	for i, p := range wbc.keys {
+		mcw[i] = p
+	}
+	return mcw
+}
+
+type Model struct {
+	lock  sync.RWMutex
+	words map[string]uint
+}
+
+func NewModel() Model {
+	return Model{words: make(map[string]uint)}
+}
+
+func (m *Model) AddWords(words []string) {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	for _, word := range words {
+		v, _ := m.words[word]
+		m.words[word] = v + 1
+	}
+}
+
+func (m *Model) GetMostCommonPairs(how_many uint) []string {
+	m.lock.RLock()
+	defer m.lock.RUnlock()
+	wbc := newWordsByCount(&m.words)
+	mcw := wbc.MostCommonWords()
+	return mcw[:how_many]
+}
diff --git a/go/mixed-server_test.go b/go/mixed-server_test.go
new file mode 100644
index 0000000..6e33b1f
--- /dev/null
+++ b/go/mixed-server_test.go
@@ -0,0 +1,24 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestModel1(t *testing.T) {
+	m := NewModel()
+	m.AddWords([]string{"a", "b", "a"})
+	got := m.GetMostCommonPairs(2)
+	if !(got[0] == "a" && got[1] == "b") {
+		t.Errorf("bad order, got %v", got)
+	}
+}
+
+func TestModel2(t *testing.T) {
+	m := NewModel()
+	m.AddWords([]string{"a", "b", "a"})
+	m.AddWords([]string{"b", "c", "b"})
+	got := m.GetMostCommonPairs(2)
+	if !(got[0] == "b" && got[1] == "a") {
+		t.Errorf("bad order, got %v", got)
+	}
+}
-- 
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