auctionsim/main/main.go

package main

import (
	"fmt"
	"git.chromaticdragon.app/kistaro/auctionsim/auctionsim"
	"log"
	"math"
	"os"
	"strconv"
)

func deltaStr(delta float64) string {
	if delta > 0 {
		return fmt.Sprintf("gained ¤%f", delta)
	}
	if delta < 0 {
		return fmt.Sprintf("lost ¤%f", -delta)
	}
	return "broken even"
}

func main() {
	num := int64(1000)
	if len(os.Args) > 1 {
		n, err := strconv.ParseInt(os.Args[1], 0, 64)
		if err != nil {
			log.Fatalf("can't parse %q as a number of bidders: %v", os.Args[1], err)
		}
		num = n
	}
	if num <= 1 {
		log.Fatalf("can't run an auction with %d bidders", num)
	}

	price, allBidders := auctionsim.RunAuctionVerbosely(
		&auctionsim.CappedBidderGenerator{
			G:   auctionsim.NormalestBidderGenerator(),
			Lim: num,
		},
	)
	bidder := allBidders[len(allBidders)-1]

	fmt.Printf("The auction winner paid ¤%f. They have %s.\n", price, deltaStr(bidder.Value-price))
	fmt.Printf("The item was worth ¤%f to them.\n", bidder.Value)
	fmt.Printf("They would have paid up to ¤%f for it.\n", bidder.BidCeiling())

	fmt.Println()
	i := len(allBidders) - 2
	for i >= 0 && allBidders[i].Value < price {
		i--
	}

	if i < 0 {
		fmt.Printf("The item was not worth that to anybody.\n")
	} else {
		rube := allBidders[i]
		fmt.Printf("The highest bidder who would have made a profit at that price stopped bidding at ¤%f.\n", rube.BidCeiling())
		fmt.Printf("They should have kept bidding until ¤%f.\n", rube.Value)
		if rankDelta := len(allBidders) - i - 1; rankDelta == 1 {
			fmt.Println("They were outbid by 1 bidder.")
		} else {
			fmt.Printf("They were outbid by %d bidders.\n", rankDelta)
		}
		fmt.Printf("If they had paid the amount of the winning bid, they would have %s.\n", deltaStr(rube.Value-price))
	}

	fmt.Println()
	maxValue := math.Inf(-1)
	maxIdx := -1
	for i, b := range allBidders {
		if b.Value > maxValue {
			maxValue = b.Value
			maxIdx = i
		}
	}

	if maxIdx == -1 {
		fmt.Println("Wow! It was infinitely beyond worthless to everybody.")
	} else {
		fmt.Printf("The bidder who would have gotten the most value was outbid by %d bidders.\n", len(allBidders)-maxIdx-1)
		rube := allBidders[maxIdx]
		fmt.Printf("The item was worth at most ¤%f to them. Their maximum bid was ¤%f.\n", rube.Value, rube.BidCeiling())
		fmt.Printf("If they had paid the winning bid, they would have %s.\n", deltaStr(rube.Value-price))
	}
}