push improvements

Author: gmajcen

day1/day1.go

@@ -22,8 +22,8 @@ func parseData() DataType {
 }
 
 func solvePart1(data DataType) (rc int) {
-	for _, v1 := range data {
-		for _, v2 := range data {
+	for i, v1 := range data {
+		for _, v2 := range data[i+1:] {
 			if v1+v2 == 2020 {
 				return v1 * v2
 			}
@@ -34,9 +34,9 @@ func solvePart1(data DataType) (rc int) {
 }
 
 func solvePart2(data DataType) (rc int) {
-	for _, v1 := range data {
-		for _, v2 := range data {
-			for _, v3 := range data {
+	for i, v1 := range data {
+		for j, v2 := range data[i+1:] {
+			for _, v3 := range data[j+1:] {
 				if v1+v2+v3 == 2020 {
 					return v1 * v2 * v3
 				}

day11/day11.go

@@ -11,11 +11,13 @@ var MAXX int
 var MAXY int
 
 const (
-	StateEmptySeat    = 1
-	StateOccupiedSeat = 2
+	StateEmptySeat    SeatState = 1 // iota
+	StateOccupiedSeat SeatState = 2 // iota
 )
 
-type DataType map[Location]int
+type SeatState int
+
+type DataType map[Location]SeatState
 
 func parseData() DataType {
 	data := FetchInputData(11)
@@ -62,7 +64,7 @@ func findNeighboursOccupiedInf(data DataType, location Location) (rc int) {
 	return
 }
 
-func applyRulesPart1(data DataType, location Location) int {
+func applyRulesPart1(data DataType, location Location) SeatState {
 	neighboursOccupied := findNeighboursOccupied(data, location)
 
 	if data[location] == StateEmptySeat && neighboursOccupied == 0 {
@@ -76,7 +78,7 @@ func applyRulesPart1(data DataType, location Location) int {
 	return data[location]
 }
 
-func applyRulesPart2(data DataType, location Location) int {
+func applyRulesPart2(data DataType, location Location) SeatState {
 	neighboursOccupiedInf := findNeighboursOccupiedInf(data, location)
 
 	if data[location] == StateEmptySeat && neighboursOccupiedInf == 0 {
@@ -90,7 +92,7 @@ func applyRulesPart2(data DataType, location Location) int {
 	return data[location]
 }
 
-func transform(data DataType, applyRules func(DataType, Location) int) DataType {
+func transform(data DataType, applyRules func(DataType, Location) SeatState) DataType {
 	newData := make(DataType, len(data))
 	for location := range data {
 		newData[location] = applyRules(data, location)
@@ -108,7 +110,7 @@ func countOccupied(data DataType) (rc int) {
 	return
 }
 
-func solve(data DataType, applyRules func(DataType, Location) int) int {
+func solve(data DataType, applyRules func(DataType, Location) SeatState) int {
 	oldData := transform(data, applyRules)
 	newData := transform(oldData, applyRules)
 

day12/day12.go

@@ -3,7 +3,6 @@ package main
 import (
 	. "../util"
 	"fmt"
-	"strconv"
 	"strings"
 )
 
@@ -20,10 +19,7 @@ func parseData() DataType {
 
 	result := make(DataType, len(dataSplit))
 	for i, v := range dataSplit {
-		action := v[0]
-		value, _ := strconv.Atoi(v[1:])
-
-		result[i] = Instruction{action, value}
+		_, _ = fmt.Sscanf(v, "%c%d", &result[i].action, &result[i].value)
 	}
 
 	return result
@@ -55,16 +51,12 @@ func nextDirectionPart1(direction byte, code byte, value int) (n byte) {
 		switch n {
 		case 'N':
 			n = 'E'
-			break
 		case 'E':
 			n = 'S'
-			break
 		case 'S':
 			n = 'W'
-			break
 		case 'W':
 			n = 'N'
-			break
 		}
 		value -= 90
 	}
@@ -92,11 +84,12 @@ func solvePart1(data DataType) (rc int) {
 	position := Location{}
 
 	for _, instruction := range data {
-		if instruction.action == 'R' || instruction.action == 'L' {
+		switch instruction.action {
+		case 'L', 'R':
 			direction = nextDirectionPart1(direction, instruction.action, instruction.value)
-		} else if instruction.action == 'F' {
+		case 'F':
 			position = nextLocation(position, direction, instruction.value)
-		} else {
+		default:
 			position = nextLocation(position, instruction.action, instruction.value)
 		}
 	}
@@ -109,11 +102,12 @@ func solvePart2(data DataType) (rc int) {
 	position := Location{}
 
 	for _, instruction := range data {
-		if instruction.action == 'R' || instruction.action == 'L' {
+		switch instruction.action {
+		case 'L', 'R':
 			waypoint = nextWaypointRotatePart2(waypoint, instruction.action, instruction.value)
-		} else if instruction.action == 'F' {
+		case 'F':
 			position = position.Add(waypoint.Mul(instruction.value))
-		} else {
+		default:
 			waypoint = nextLocation(waypoint, instruction.action, instruction.value)
 		}
 	}

day13/day13.go

@@ -3,7 +3,7 @@ package main
 import (
 	. "../util"
 	"fmt"
-	"math/big"
+	"math"
 	"strconv"
 	"strings"
 )
@@ -33,26 +33,7 @@ func parseData() DataType {
 		}
 	}
 
-	result := DataType{
-		myTimestamp: myTimestamp,
-		buses:       buses,
-	}
-
-	return result
-}
-
-func ChineseRemainderTheorem(a []*big.Int, n []*big.Int) *big.Int {
-	p := new(big.Int).Set(n[0])
-	for _, n1 := range n[1:] {
-		p.Mul(p, n1)
-	}
-	var x, q, s, z big.Int
-	for i, n1 := range n {
-		q.Div(p, n1)
-		z.GCD(nil, &s, n1, &q)
-		x.Add(&x, s.Mul(a[i], s.Mul(&s, &q)))
-	}
-	return x.Mod(&x, p)
+	return DataType{myTimestamp, buses}
 }
 
 func calculateWaitingTime(myTimestamp int, busId int) int {
@@ -61,7 +42,7 @@ func calculateWaitingTime(myTimestamp int, busId int) int {
 
 func solvePart1(data DataType) (rc int) {
 	minBusId := data.buses[0].id
-	minWaitingTime := calculateWaitingTime(data.myTimestamp, minBusId)
+	minWaitingTime := math.MaxInt64
 
 	for _, bus := range data.buses {
 		waitingTime := calculateWaitingTime(data.myTimestamp, bus.id)
@@ -74,16 +55,16 @@ func solvePart1(data DataType) (rc int) {
 	return minBusId * minWaitingTime
 }
 
-func solvePart2(data DataType) (rc *big.Int) {
-	a := make([]*big.Int, 0, len(data.buses))
-	n := make([]*big.Int, 0, len(data.buses))
+func solvePart2(data DataType) (rc int) {
+	step := 1
 	for _, bus := range data.buses {
-		a = append(a, big.NewInt(int64(-bus.departTimestamp)))
-		n = append(n, big.NewInt(int64(bus.id)))
+		for (rc+bus.departTimestamp)%bus.id != 0 {
+			rc += step
+		}
+		step *= bus.id
 	}
 
-	x := ChineseRemainderTheorem(a, n)
-	return x
+	return
 }
 
 func main() {

day16/day16.go

@@ -3,7 +3,6 @@ package main
 import (
 	. "../util"
 	"fmt"
-	"regexp"
 	"strconv"
 	"strings"
 )
@@ -30,36 +29,29 @@ func parseData() DataType {
 	data := FetchInputData(16)
 	dataSplit := strings.Split(data, "\n\n")
 
-	typesLineRe := regexp.MustCompile("^(.*): ([0-9]+)-([0-9]+) or ([0-9]+)-([0-9]+)$")
 	typeLines := strings.Split(dataSplit[0], "\n")
 	types := make([]Type, len(typeLines))
 	for i, typesLine := range typeLines {
-		match := typesLineRe.FindStringSubmatch(typesLine)
-		name := match[1]
-		ruleFrom1, _ := strconv.Atoi(match[2])
-		ruleTo1, _ := strconv.Atoi(match[3])
-		ruleFrom2, _ := strconv.Atoi(match[4])
-		ruleTo2, _ := strconv.Atoi(match[5])
-
-		types[i] = Type{name, Rule{ruleFrom1, ruleTo1, ruleFrom2, ruleTo2}}
+		typesLineSplit := strings.Split(typesLine, ": ")
+		types[i].name = typesLineSplit[0]
+		_, _ = fmt.Sscanf(typesLineSplit[1], "%d-%d or %d-%d", &types[i].rule.from1, &types[i].rule.to1, &types[i].rule.from2, &types[i].rule.to2)
 	}
 
 	myTicketLine := strings.Split(dataSplit[1], "\n")[1]
-	myTicket := make([]int, 0)
-	for _, v := range strings.Split(myTicketLine, ",") {
-		vi, _ := strconv.Atoi(v)
-		myTicket = append(myTicket, vi)
+	myTicketLineSplit := strings.Split(myTicketLine, ",")
+	myTicket := make([]int, len(myTicketLineSplit))
+	for i, v := range myTicketLineSplit {
+		myTicket[i], _ = strconv.Atoi(v)
 	}
 
 	nearbyTicketsLines := strings.Split(dataSplit[2], "\n")[1:]
 	nearbyTickets := make([][]int, len(nearbyTicketsLines))
 	for i, nearbyTicketsLine := range nearbyTicketsLines {
-		tmp := make([]int, 0)
-		for _, v := range strings.Split(nearbyTicketsLine, ",") {
-			vi, _ := strconv.Atoi(v)
-			tmp = append(tmp, vi)
+		nearbyTicketsLineSplit := strings.Split(nearbyTicketsLine, ",")
+		nearbyTickets[i] = make([]int, len(nearbyTicketsLineSplit))
+		for ii, v := range nearbyTicketsLineSplit {
+			nearbyTickets[i][ii], _ = strconv.Atoi(v)
 		}
-		nearbyTickets[i] = tmp
 	}
 
 	return DataType{types, myTicket, nearbyTickets}

day17/day17.go

@@ -37,8 +37,7 @@ func findInactiveNeighbors(data map[LocationXYXW]bool, el LocationXYXW, dimensio
 
 	minDw, maxDw := 0, 0
 	if dimensions == 4 {
-		minDw = -1
-		maxDw = 1
+		minDw, maxDw = -1, 1
 	}
 
 	for dw := minDw; dw <= maxDw; dw++ {