pgoultiaev/aoc2017

package main

import (
    "bufio"
    "log"
    "os"
    "strings"

    "github.com/pgoultiaev/aoc2017/util"
)

type Component struct {
    port1, port2 int
    inUse        bool
}

var maxBridgeStrength int
var longestBridgeStrength int
var maxBridgeLength int

func main() {
    println(solve("24.txt"))
    println(solve2("24.txt"))
}

// Part two
func solve2(filename string) int {
    components := readInput(filename)
    return buildBridge2(components, 0, 0, 0)
}

func buildBridge2(components []Component, bridgeStrength, bridgeLength, currentPort int) int {
    if bridgeLength > maxBridgeLength || bridgeLength == maxBridgeLength && bridgeStrength > longestBridgeStrength {
        maxBridgeLength = bridgeLength
        longestBridgeStrength = bridgeStrength
    }
    for i, component := range components {
        if component.inUse {
            continue
        }
        if component.port1 == currentPort {
            components[i].inUse = true
            buildBridge2(components, bridgeStrength+component.port1+component.port2, bridgeLength+1, component.port2)
            components[i].inUse = false
        } else if component.port2 == currentPort {
            components[i].inUse = true
            buildBridge2(components, bridgeStrength+component.port1+component.port2, bridgeLength+1, component.port1)
            components[i].inUse = false
        }
    }

    return longestBridgeStrength
}

// Part one
func solve(filename string) int {
    components := readInput(filename)
    return buildBridge(components, 0, 0)
}

func buildBridge(components []Component, bridgeStrength, currentPort int) int {
    if bridgeStrength > maxBridgeStrength {
        maxBridgeStrength = bridgeStrength
    }
    for i, component := range components {
        if component.inUse {
            continue
        }
        if component.port1 == currentPort {
            components[i].inUse = true
            buildBridge(components, bridgeStrength+component.port1+component.port2, component.port2)
            components[i].inUse = false
        } else if component.port2 == currentPort {
            components[i].inUse = true
            buildBridge(components, bridgeStrength+component.port1+component.port2, component.port1)
            components[i].inUse = false
        }
    }

    return maxBridgeStrength
}

func readInput(filename string) []Component {
    file, err := os.Open(filename)
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()

    scanner := bufio.NewScanner(file)

    components := []Component{}
    for scanner.Scan() {
        line := strings.Split(scanner.Text(), "/")
        lineInts := util.ConvStringArrayToIntArray(line)

        c := Component{lineInts[0], lineInts[1], false}
        components = append(components, c)
    }

    return components
}