From bfa6a3e3ea89f306520067144a836b35b5e7d37a Mon Sep 17 00:00:00 2001
From: Junwei Zhao <wahyd4@gmail.com>
Date: Tue, 23 Apr 2019 14:15:55 +1000
Subject: [PATCH] init commit

---
 main.go | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 main.go

diff --git a/main.go b/main.go
new file mode 100644
index 0000000..3eb442d
--- /dev/null
+++ b/main.go
@@ -0,0 +1,115 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"math/rand"
+	"sort"
+	"time"
+)
+
+// const
+const (
+	NumberCount    = 7
+	MaximumResults = 50
+)
+
+var (
+	winners = make(map[[NumberCount]int]int)
+)
+
+func main() {
+	timesInput := flag.Int("t", 100000, "an int")
+	flag.Parse()
+	times := *timesInput
+
+	now := time.Now()
+
+	startTime := now.Unix()
+
+	fmt.Printf("Started at %v to run lottery for %v times \n", now, times)
+	for i := 0; i < times; i++ {
+		winner := run()
+		if currentTimes, ok := winners[winner]; ok {
+			winners[winner] = currentTimes + 1
+		} else {
+			winners[winner] = 1
+		}
+	}
+
+	fmt.Printf("Calculation finished at : %v \n", time.Now())
+	// only print out top numbers
+	type kv struct {
+		Key   [NumberCount]int
+		Value int
+	}
+
+	var ss []kv
+	for k, v := range winners {
+		// to reduce the time consuming, if the number only exists once then skip it
+		if v > 1 {
+			ss = append(ss, kv{k, v})
+		}
+
+	}
+
+	sort.Slice(ss, func(i, j int) bool {
+		return ss[i].Value > ss[j].Value
+	})
+
+	fmt.Printf("Sorting finished at : %v \n", time.Now())
+
+	index := 0
+	for _, kv := range ss {
+		// only pick the top numbers
+		if index > MaximumResults {
+			break
+		}
+		fmt.Printf("%v, %d \n", kv.Key, kv.Value)
+		index++
+	}
+	fmt.Printf("The process takes about: %v seconds", time.Now().Unix()-startTime)
+}
+
+func run() [7]int {
+	var winNumbers []int
+	// generate the randomised numbers
+	list := rand.Perm(45)
+	// because perm generate [0,45) but we need [1,45]
+	for index, item := range list {
+		list[index] = item + 1
+	}
+
+	rand.Seed(time.Now().UnixNano())
+
+	indexes := make([]int, 0)
+
+	for i := 0; i < NumberCount; i++ {
+		pickedIndex := pickIndex(indexes, len(list))
+		indexes = append(indexes, pickedIndex)
+
+		//pick random number
+		chosen := list[pickedIndex]
+
+		winNumbers = append(winNumbers, chosen)
+	}
+
+	sort.Ints(winNumbers)
+	var arr [NumberCount]int
+	copy(arr[:], winNumbers)
+
+	return arr
+
+}
+
+func pickIndex(indexes []int, length int) int {
+	chosen := rand.Intn(length - 1)
+	// make sure the index only exist once
+	for _, value := range indexes {
+		if value == chosen {
+			return pickIndex(indexes, length)
+		}
+	}
+
+	return chosen
+}