adventofcode/2018/day11/day11.go

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package main
import (
"fmt"
"log"
"os"
"strconv"
)
const (
MaxInt = int(^uint(0) >> 1)
MinInt = -MaxInt - 1
)
var timeMachine *TimeMachine
func main() {
if len(os.Args) < 2 {
fmt.Println("Usage: day11 <serial #>")
os.Exit(1)
}
timeMachine = &TimeMachine{
serial: Atoi(os.Args[1]),
fuelLevels: make(map[string]int),
}
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timeMachine.fillGrid()
part1()
part2()
}
func part1() {
top := MinInt
topX, topY := 0, 0
for i := 1; i < 300; i++ {
for j := 1; j < 300; j++ {
w := timeMachine.getSquareFuelLevel(i, j, 3)
if w > top {
top = w
topX, topY = i, j
}
}
}
fmt.Printf("%d,%d : %d\n", topX, topY, top)
fmt.Println("= Part 1 =")
timeMachine.printSquare(topX, topY, 3)
}
func part2() {
top := MinInt
topX, topY, topS := 1, 1, 1
for i := 1; i <= 300; i++ {
for j := 1; j <= 300; j++ {
maxSize := 300 - (i - 1)
if i < j {
maxSize = 300 - (j - 1)
}
for s := 1; s <= maxSize; s++ {
wrk := timeMachine.getSquareFuelLevel(i, j, s)
if wrk > top {
top = wrk
topX, topY, topS = i, j, s
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}
}
}
}
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fmt.Println("= Part 2 =")
fmt.Printf("%d,%d,%d : %d\n", topX, topY, topS, top)
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}
type TimeMachine struct {
serial int
fuelLevels map[string]int
}
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func (t *TimeMachine) printSquare(x, y, size int) {
for j := y; j < y+size; j++ {
for i := x; i < x+size; i++ {
fmt.Printf("%2d ", t.getSquareFuelLevel(i, j, 1))
}
fmt.Println("")
}
}
func (t *TimeMachine) fillGrid() {
for i := 1; i <= 300; i++ {
for j := 1; j <= 300; j++ {
t.fuelLevels[t.getKeyForSquare(i, j, 1)] = t.calcFuelLevel(i, j)
}
}
}
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func (t *TimeMachine) getKeyForSquare(x, y, size int) string {
bx := strconv.Itoa(x)
by := strconv.Itoa(y)
bs := strconv.Itoa(size)
return bx + "," + by + "," + bs
}
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func (t *TimeMachine) getSquareFuelLevel(x, y, size int) int {
k := t.getKeyForSquare(x, y, size)
if v, ok := t.fuelLevels[k]; ok {
return v
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}
if size == 1 {
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// We shouldn't be here if we filled the grid before running
return 0
}
var ret int
ret = t.getSquareFuelLevel(x, y, size-1)
// Add the right-most cells
for i := 0; i < size; i++ {
ret += t.calcFuelLevel(x+(size-1), y+i)
}
// Add the bottom cells
for i := 0; i < size-1; i++ {
ret += t.calcFuelLevel(x+i, y+(size-1))
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}
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t.fuelLevels[k] = ret
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return ret
}
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// calcFuelLevel calculates one cells fuel level
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func (t *TimeMachine) calcFuelLevel(x, y int) int {
rackId := x + 10
startingLevel := rackId * y
currLevel := startingLevel + t.serial
currLevel *= rackId
var ret int
if currLevel < 100 {
ret = -5
} else {
ret = ((currLevel / 100) % 10) - 5
}
return ret
}
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// calcSquareFuelLevel calculates all cells from x, y -> x+size, y+size
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func (t *TimeMachine) calcSquareFuelLevel(x, y, size int) int {
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var ret int
for i := 0; i < size; i++ {
for j := 0; j < size; j++ {
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ret += t.calcFuelLevel(x+i, y+j)
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}
}
return ret
}
func Atoi(i string) int {
var ret int
var err error
if ret, err = strconv.Atoi(i); err != nil {
log.Fatal("Invalid Atoi")
}
return ret
}