Pyramid Dice Simulation

!pyramid_dice.go

package main

import (
	"fmt"
	"math/rand"
	"time"
)

func d6(rng *rand.Rand) int {
	return rng.Intn(6) + 1
}

type rolls [2]int

func oneRound(rng *rand.Rand) int {
	saw := map[rolls]bool{}
	var key rolls
	for i := 0; i < 21; i++ {
		key[0], key[1] = d6(rng), d6(rng)
		if key[1] > key[0] {
			key[0], key[1] = key[1], key[0]
		}
		if saw[key] {
			return i
		}
		saw[key] = true
	}
	return 21
}

func main() {
	rng := rand.New(rand.NewSource(time.Now().UnixNano()))
	var counts [22]int64
	for i := 0; i < 1_500_000_000; i++ {
		counts[oneRound(rng)]++
	}
	fmt.Printf("done %#v\n", counts)
}

LICENSE

  Copyright 2021 Kevin Lubick

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.