adventofcode/2015/day13/main.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var people map[string]person

func main() {
	var pplSlice []string
	people = make(map[string]person)
	var input []string
	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		input = append(input, scanner.Text())
	}

	for i := range input {
		p := parseLine(input[i])
		people[p.name] = p
	}
	for i := range people {
		pplSlice = append(pplSlice, people[i].name)
	}
	// Output all preferences
	/*
		for k, v := range people {
			fmt.Println(k)
			fmt.Println("  High: " + v.highName + " :: " + strconv.Itoa(v.highVal))
			for pk, pv := range v.prefs {
				fmt.Println("  " + pk + ": " + strconv.Itoa(pv))
			}
		}
	*/
	//getPerms(pplSlice)
	first := pplSlice[0]
	res := getPerms(pplSlice[1:])
	var high int
	var arrangement []string
	for i := range res {
		tstArr := append([]string{first}, res[i]...)
		tst := happinessFromStrings(tstArr)
		if tst > high {
			high = tst
			arrangement = tstArr
		}
	}
	fmt.Println("Highest: " + strconv.Itoa(high))
	fmt.Println(arrangement)
}

func getPerms(ppl []string) [][]string {
	var ret [][]string
	if len(ppl) == 1 {
		return append(ret, ppl)
	}

	for j := range ppl {
		var bld []string
		for i := range ppl {
			if i != j {
				bld = append(bld, ppl[i])
			}
		}
		perms := getPerms(bld)
		for i := range perms {
			perms[i] = append([]string{ppl[j]}, perms[i]...)
			ret = append(ret, perms[i])
		}
	}
	return ret
}

func happinessFromStrings(pS []string) int {
	var ppl []person
	for i := range pS {
		ppl = append(ppl, people[pS[i]])
	}
	return happinessValue(ppl)
}

func happinessValue(ppl []person) int {
	var ret int
	for i := range ppl {
		p1, p2 := getNeighbors(ppl[i], ppl)
		ret += ppl[i].prefs[p1.name]
		ret += ppl[i].prefs[p2.name]
	}
	return ret
}

func getNeighbors(p person, ppl []person) (person, person) {
	var p1, p2 person
	for idx := range ppl {
		if ppl[idx].name == p.name {
			if idx == 0 {
				p1 = ppl[len(ppl)-1]
				p2 = ppl[idx+1]
			} else if idx == len(ppl)-1 {
				p1 = ppl[idx-1]
				p2 = ppl[0]
			} else {
				p1 = ppl[idx-1]
				p2 = ppl[idx+1]
			}
			break
		}
	}
	return p1, p2
}

type person struct {
	name     string
	prefs    map[string]int
	highName string
	highVal  int
	lowName  string
	lowVal   int
}

func parseLine(s string) person {
	parts := strings.Split(s, " ")
	who := parts[0]
	direction := parts[2]
	amount := mustAtoi(parts[3])
	nextTo := parts[10][:len(parts[10])-1]
	if direction == "lose" {
		amount = amount * -1
	}
	var ret person
	var ok bool
	if ret, ok = people[who]; !ok {
		ret = person{name: who}
		ret.prefs = make(map[string]int)
	}
	ret.prefs[nextTo] = amount
	if ret.highVal < amount || ret.highName == "" {
		ret.highVal, ret.highName = amount, nextTo
	}
	if ret.lowVal > amount || ret.lowName == "" {
		ret.lowVal, ret.lowName = amount, nextTo
	}
	return ret
}

func mustAtoi(s string) int {
	var i int
	var err error
	if i, err = strconv.Atoi(s); err != nil {
		fmt.Println("Tried to atoi " + s)
	}
	return i
}