From ad8f04f0255d66917a0bfeae598046404e38b9b6 Mon Sep 17 00:00:00 2001
From: Rostislav Kuratch <kr0st@bioreactor.me>
Date: Thu, 23 Jun 2022 21:08:43 +0300
Subject: [PATCH] "837. New 21 Game" medium, experiments with random numbers
 generation

---
 837-new-21-game.go | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/837-new-21-game.go b/837-new-21-game.go
index 2026055..dd6305a 100644
--- a/837-new-21-game.go
+++ b/837-new-21-game.go
@@ -246,7 +246,15 @@ func (rng *rngSource) Uint64() uint64 {
 	return uint64(x)
 }
 
-func new21GameExperimental(n int, k int, maxPts int) float64 {
+type RngType int
+
+const (
+	StandardRng RngType = iota
+	FastRng
+	AlwaysNewRng
+)
+
+func new21GameExperimental(n int, k int, maxPts int, rngType RngType) float64 {
 	generator := rngSource{}
 	generator.Seed(time.Now().Unix())
 	rand.Seed(time.Now().Unix())
@@ -255,12 +263,21 @@ func new21GameExperimental(n int, k int, maxPts int) float64 {
 	rndTable := [100000]uint64{}
 	maxRandoms := maxPts * 10
 
-	for i := 0; i < maxRandoms; i++ {
-		rndTable[i] = 1 + generator.Uint64()%mp
+	if rngType == FastRng {
+		for i := 0; i < maxRandoms; i++ {
+			rndTable[i] = 1 + generator.Uint64()%mp
+		}
+	} else {
+		for i := 0; i < maxRandoms; i++ {
+			rndTable[i] = 1 + uint64(rand.Int63n(int64(mp)))
+		}
 	}
 
 	nextRandom := 0
 	getNextRandom := func() uint64 {
+		if rngType == AlwaysNewRng {
+			return 1 + uint64(rand.Int63n(int64(mp)))
+		}
 		res := rndTable[nextRandom]
 		nextRandom++
 		if nextRandom >= maxRandoms {
@@ -296,7 +313,7 @@ func new21GameExperimental(n int, k int, maxPts int) float64 {
 		return float64(nOrLessCount) / float64(kOrMoreCount)
 	}
 
-	stabilityThreshold := 100
+	stabilityThreshold := 1000
 	precision := 0.00001
 	stability := 0
 
@@ -317,5 +334,5 @@ func new21GameExperimental(n int, k int, maxPts int) float64 {
 }
 
 func New21Game(n int, k int, maxPts int) float64 {
-	return new21GameExperimental(n, k, maxPts)
+	return new21GameExperimental(n, k, maxPts, FastRng)
 }