Day 8: Part 1 and 2

Signed-off-by: James Griffin <james@unsupervised.ca>

eight/day_eight.go

@@ -0,0 +1,129 @@
+package eight
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+type program struct {
+	instructions []instruction
+	accumulator  int
+	preempted    bool
+}
+
+type instruction struct {
+	operation string
+	argument  int
+	executed  bool
+}
+
+func (p *program) load(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		var op string
+		var value int
+
+		count, err := fmt.Sscanf(scanner.Text(), "%s %d", &op, &value)
+		if count != 2 || err != nil {
+			return fmt.Errorf("Unable to parse %s: %w", scanner.Text(), err)
+		}
+
+		p.instructions = append(p.instructions, instruction{
+			operation: op,
+			argument:  value,
+			executed:  false,
+		})
+	}
+
+	return nil
+}
+
+func (p *program) exec() int {
+	i := 0
+	for {
+		if i >= len(p.instructions) {
+			p.preempted = false
+			return p.accumulator
+		} else if i < 0 {
+			return p.accumulator
+		}
+
+		if p.instructions[i].executed {
+			break
+		}
+
+		p.instructions[i].executed = true
+		switch p.instructions[i].operation {
+		case "acc":
+			p.accumulator += p.instructions[i].argument
+			i++
+		case "jmp":
+			i += p.instructions[i].argument
+		default:
+			i++
+		}
+	}
+
+	return p.accumulator
+}
+
+func (p *program) reset() {
+	p.accumulator = 0
+	p.preempted = true
+	for i := 0; i < len(p.instructions); i++ {
+		p.instructions[i].executed = false
+	}
+}
+
+func (p *program) flipJmpNop(index int) {
+	if index < 0 || index > len(p.instructions) {
+		return
+	}
+
+	switch p.instructions[index].operation {
+	case "nop":
+		p.instructions[index].operation = "jmp"
+	case "jmp":
+		p.instructions[index].operation = "nop"
+	}
+}
+
+func (p *program) heal() int {
+	for i := 0; i < len(p.instructions); i++ {
+		p.reset()
+		p.flipJmpNop(i)
+		p.exec()
+
+		if !p.preempted {
+			return i
+		}
+		p.flipJmpNop(i)
+	}
+
+	return -1
+}
+
+// PartOne Find the value of the accumulator before any instruction is executed twice
+func PartOne() string {
+	p := program{}
+	p.load("eight/handheld.code")
+
+	return fmt.Sprintf("The accumulator is at %d before the loop begins", p.exec())
+}
+
+// PartTwo Find the corrupt instruction, flip it, and execute to termination
+func PartTwo() string {
+	p := program{}
+	p.load("eight/handheld.code")
+	p.exec()
+	index := p.heal()
+
+	return fmt.Sprintf("The accumulator is at %d after termination by correcting instruction %d", p.accumulator, index+1)
+}

eight/day_eight_test.go

@@ -0,0 +1,97 @@
+package eight
+
+import "testing"
+
+func (p *program) visited() int {
+	highest := 0
+	for i, instruction := range p.instructions {
+		if instruction.executed {
+			if i > highest {
+				highest = i
+			}
+		}
+	}
+	return highest
+}
+
+func Test_program_load(t *testing.T) {
+	p := program{}
+	err := p.load("sample.code")
+	if err != nil {
+		t.Log(err)
+		t.FailNow()
+	}
+
+	if len(p.instructions) != 9 {
+		t.Logf("Expected 9 instructions, Got %d instructions", len(p.instructions))
+		t.FailNow()
+	}
+}
+
+func Test_program_execute(t *testing.T) {
+	p := program{}
+	p.load("sample.code")
+
+	result := p.exec()
+	if result != 5 {
+		t.Logf("Expected result of 5, Got %d", result)
+		t.FailNow()
+	}
+}
+
+func Test_program_terminate(t *testing.T) {
+	p := program{}
+	p.load("sample.code")
+
+	p.exec()
+	highest := p.visited()
+	p.flipJmpNop(highest)
+	p.reset()
+	result := p.exec()
+	highest = p.visited()
+
+	if highest+1 != len(p.instructions) {
+		t.Logf("Made it to %d of %d instructions", highest+1, len(p.instructions))
+		t.Fail()
+	}
+
+	if result != 8 || p.preempted {
+		t.Logf("Expected result of 8, Got %d and the program was preempted", result)
+		t.FailNow()
+	}
+}
+
+func Test_program_heal(t *testing.T) {
+	p := program{}
+	p.load("sample.code")
+
+	p.exec()
+	index := p.heal()
+	highest := p.visited()
+
+	if highest+1 != len(p.instructions) {
+		t.Logf("Made it to %d of %d instructions by flipping instruction %d", highest+1, len(p.instructions), index+1)
+		t.Fail()
+	}
+
+	if p.accumulator != 8 || p.preempted {
+		t.Logf("Expected result of 8, Got %d and the program was preempted", p.accumulator)
+		t.FailNow()
+	}
+}
+
+func Test_handheld_terminate(t *testing.T) {
+	p := program{}
+	p.load("handheld.code")
+
+	p.exec()
+	highest := p.visited()
+	t.Logf("Made it to %d of %d instructions on the first run", highest+1, len(p.instructions))
+	p.heal()
+	highest = p.visited()
+
+	if highest+1 != len(p.instructions) || p.preempted {
+		t.Logf("Made it to %d of %d instructions", highest+1, len(p.instructions))
+		t.Fail()
+	}
+}

eight/handheld.code

@@ -0,0 +1,660 @@
+jmp +11
+nop +495
+nop +402
+jmp +570
+jmp +569
+jmp +451
+acc -12
+jmp +364
+acc +30
+acc +21
+jmp +430
+jmp +87
+acc -12
+acc -4
+acc +11
+jmp +50
+jmp +149
+jmp +341
+nop +1
+acc +33
+jmp +461
+acc +43
+acc -15
+jmp +440
+acc +18
+acc +22
+acc -14
+nop +576
+jmp -22
+acc +33
+acc +0
+acc +34
+jmp +369
+nop +497
+nop +469
+acc -12
+jmp +93
+acc -13
+jmp +337
+acc +5
+acc +18
+acc +26
+nop +115
+jmp +67
+nop +282
+nop -6
+nop +289
+jmp +303
+acc +10
+acc -15
+jmp +153
+nop +445
+acc -8
+acc +11
+jmp +374
+acc +35
+acc -9
+nop +199
+jmp +1
+jmp +369
+jmp +1
+acc +22
+acc -18
+acc +17
+jmp +303
+acc +37
+acc +13
+acc +22
+nop +307
+jmp +154
+nop +381
+acc -6
+nop -54
+acc +38
+jmp +494
+acc +37
+acc +15
+jmp +475
+jmp +474
+nop +534
+acc +37
+jmp +359
+jmp +296
+acc +40
+jmp +157
+acc +5
+nop +139
+acc +49
+acc +45
+jmp +237
+acc +42
+acc +8
+acc +43
+jmp +466
+nop +362
+acc +43
+acc +44
+jmp +233
+acc +30
+acc +42
+acc -6
+jmp -97
+jmp +527
+acc +2
+acc +13
+nop +425
+jmp +113
+nop +374
+acc +31
+jmp +48
+acc +29
+acc +15
+acc +35
+jmp +357
+acc +19
+acc -2
+jmp +480
+acc +1
+jmp +385
+acc +16
+acc +47
+jmp +397
+jmp +1
+jmp +1
+acc +5
+acc -5
+jmp +529
+acc +11
+jmp +123
+acc +44
+acc +49
+jmp +413
+acc +13
+acc +10
+acc -6
+acc +11
+jmp -33
+acc +25
+acc +47
+acc +40
+acc +23
+jmp +39
+acc +50
+acc +12
+jmp +386
+acc +23
+jmp +464
+acc +15
+nop +361
+acc +30
+jmp +346
+jmp +1
+acc +19
+acc +16
+acc +23
+jmp +441
+jmp +69
+acc +12
+acc +46
+acc -5
+jmp +427
+acc +49
+nop +173
+acc -12
+jmp +249
+acc +41
+acc +29
+nop +168
+acc +31
+jmp +349
+acc +40
+acc +8
+acc +14
+jmp +231
+acc -17
+jmp +215
+nop +202
+acc +0
+nop +172
+jmp +351
+acc +21
+acc +31
+nop +405
+acc +14
+jmp +272
+acc +5
+acc +33
+acc +31
+acc +21
+jmp -91
+acc -18
+acc +35
+jmp +23
+acc -10
+nop +374
+acc +27
+jmp -157
+acc +39
+acc +8
+acc +34
+acc +34
+jmp +333
+jmp -51
+acc -18
+acc +26
+jmp +377
+acc -5
+jmp +190
+acc +45
+jmp +1
+acc +29
+jmp +202
+acc +25
+acc +30
+jmp +90
+acc +49
+nop +240
+jmp +109
+jmp +291
+acc +9
+jmp +348
+acc +39
+jmp +3
+jmp +273
+jmp -218
+jmp +150
+jmp +1
+jmp +148
+acc +9
+acc +11
+acc +20
+acc +3
+jmp -167
+nop +223
+jmp +275
+nop +309
+jmp +20
+acc -18
+acc -10
+acc -2
+jmp +173
+acc +13
+acc -17
+nop +132
+acc -6
+jmp +240
+acc +37
+acc +4
+acc +49
+acc -16
+jmp +171
+jmp +239
+nop +300
+nop +311
+acc -9
+jmp -180
+acc +32
+acc +21
+jmp +1
+jmp -62
+nop +141
+acc +46
+acc +25
+nop -7
+jmp +318
+acc +3
+jmp +185
+nop +196
+acc +16
+acc +18
+jmp -47
+acc +39
+acc +35
+acc +21
+acc +14
+jmp +23
+acc +20
+acc +20
+jmp +97
+nop -71
+acc +50
+acc -11
+jmp -145
+nop -218
+acc +42
+acc +23
+acc +35
+jmp +183
+nop +16
+nop -206
+acc +2
+acc +11
+jmp +129
+acc +37
+acc +41
+acc +47
+nop -280
+jmp +93
+acc -12
+acc +31
+jmp +10
+acc +2
+acc +29
+jmp +64
+acc -14
+nop +308
+jmp -251
+acc +8
+acc +10
+jmp +259
+acc +38
+nop -131
+acc +45
+jmp +6
+acc +18
+acc +43
+nop -218
+nop -94
+jmp +178
+jmp +1
+acc +27
+acc +29
+jmp +324
+acc -12
+acc +30
+jmp +115
+acc -1
+jmp -224
+jmp +1
+jmp +205
+acc +47
+jmp -66
+acc +21
+acc +44
+jmp +147
+acc +2
+acc +50
+acc -14
+acc +50
+jmp -165
+acc +33
+acc +20
+acc -5
+acc +19
+jmp -246
+acc +26
+acc +44
+jmp -96
+acc +22
+jmp +127
+nop +25
+acc -14
+acc -15
+jmp -314
+jmp +1
+acc +11
+acc +12
+jmp +71
+acc +0
+acc +16
+acc +26
+nop +242
+jmp -172
+acc +8
+acc +15
+acc -4
+jmp -78
+acc +42
+jmp +225
+acc -7
+jmp +243
+jmp +242
+acc +23
+acc +21
+jmp +54
+acc +25
+jmp -18
+jmp -42
+jmp +26
+jmp -368
+acc +29
+acc +22
+acc +1
+acc +0
+jmp +255
+acc +39
+jmp +1
+nop -332
+acc +22
+jmp +92
+acc +45
+acc +29
+jmp +12
+jmp +1
+acc +22
+jmp +1
+jmp -245
+jmp -162
+acc -4
+acc -4
+jmp +28
+nop -4
+jmp -386
+jmp -28
+acc -1
+acc +25
+nop -28
+jmp -10
+acc +9
+acc +45
+jmp +1
+acc +13
+jmp -171
+acc +3
+acc +19
+acc -8
+acc +11
+jmp -266
+acc -18
+nop -380
+jmp -155
+acc +36
+acc -13
+acc +35
+acc -16
+jmp -414
+nop -408
+jmp +36
+acc +5
+jmp +101
+acc -7
+acc +17
+jmp -204
+acc -14
+jmp -99
+jmp +1
+nop -165
+acc +10
+acc +13
+jmp +46
+acc -13
+jmp -358
+acc -7
+acc -14
+jmp -31
+acc +21
+acc -9
+jmp -46
+nop -220
+acc -1
+jmp -105
+acc +42
+acc -14
+jmp -75
+acc +6
+jmp -34
+nop -391
+acc -11
+jmp -123
+nop -234
+acc -9
+acc +35
+jmp -317
+nop +150
+acc +11
+jmp +138
+acc +30
+acc -11
+acc +31
+jmp -134
+acc +20
+jmp -200
+acc +13
+acc +14
+acc +25
+jmp -310
+acc +13
+acc +18
+acc -1
+jmp +85
+jmp +72
+acc +1
+jmp -78
+acc -8
+jmp -149
+acc +13
+jmp -438
+acc +38
+nop -25
+jmp -264
+acc +50
+acc +47
+nop -241
+acc +31
+jmp -419
+jmp +57
+nop -359
+jmp -323
+acc +48
+acc +4
+acc -12
+acc +42
+jmp -167
+acc +50
+acc -9
+jmp -138
+nop -171
+acc +48
+jmp -398
+acc -8
+acc +41
+acc +21
+jmp -508
+acc +29
+acc +41
+acc +35
+acc +25
+jmp -388
+jmp -439
+acc +26
+acc +19
+acc +13
+acc -16
+jmp -165
+nop -61
+acc +16
+acc +20
+jmp -312
+nop -19
+jmp -101
+acc +1
+jmp -515
+acc +19
+jmp +96
+jmp +1
+acc +42
+acc +34
+acc +33
+jmp +80
+nop -314
+acc +12
+acc +36
+nop -405
+jmp -87
+acc +16
+nop -100
+acc +11
+acc +15
+jmp -524
+nop -369
+acc +8
+jmp -386
+acc +32
+jmp -77
+acc -7
+acc -16
+acc +33
+acc +30
+jmp -213
+acc -2
+jmp -403
+acc +35
+nop -81
+jmp -340
+acc +7
+acc +3
+jmp -444
+jmp -445
+jmp -218
+acc +39
+acc -9
+jmp +1
+jmp -284
+acc +43
+acc +1
+acc -12
+nop -218
+jmp -460
+jmp -404
+jmp +1
+jmp -135
+jmp -223
+jmp +1
+acc +30
+acc +36
+jmp -61
+jmp -580
+acc -8
+jmp -79
+acc +18
+acc -1
+acc +9
+jmp -321
+jmp -560
+acc +2
+jmp -182
+acc +18
+acc +29
+acc +28
+jmp -129
+acc +10
+nop -120
+jmp +16
+acc +23
+acc +9
+acc +36
+acc +24
+jmp -589
+acc +21
+jmp -419
+nop -275
+jmp -231
+jmp -341
+acc +33
+acc +30
+jmp -470
+nop -337
+jmp -389
+jmp +5
+acc -14
+nop -27
+acc +5
+jmp -78
+acc +40
+acc +2
+acc -5
+nop -205
+jmp -537
+jmp -318
+nop -404
+acc +12
+acc +0
+acc -4
+jmp -54
+acc +8
+acc +32
+nop -357
+acc +35
+jmp -153
+acc +42
+acc +17
+acc -9
+jmp -13
+nop -222
+acc +27
+jmp -63
+acc +11
+acc -17
+nop -45
+acc +4
+jmp -217
+acc +5
+acc +26
+nop -574
+jmp -489
+acc +29
+acc +36
+acc +31
+nop -407
+jmp +1

eight/sample.code

@@ -0,0 +1,9 @@
+nop +0
+acc +1
+jmp +4
+acc +3
+jmp -3
+acc -99
+acc +1
+jmp -4
+acc +6

main.go

@@ -3,7 +3,7 @@ package main
 import (
 	"fmt"
 
-	"github.com/thatguygriff/aoc2020/seven"
+	"github.com/thatguygriff/aoc2020/eight"
 )
 
 func main() {
@@ -32,6 +32,10 @@ func main() {
 	// fmt.Println(six.PartTwo())
 
 	// Day 7
-	fmt.Println(seven.PartOne())
+	// fmt.Println(seven.PartOne())
-	fmt.Println(seven.PartTwo())
+	// fmt.Println(seven.PartTwo())
+
+	// Day 8
+	fmt.Println(eight.PartOne())
+	fmt.Println(eight.PartTwo())
 }