day 8 work and jumbled together

day-1/main.go

@@ -37,8 +37,8 @@ func part1() {
 	fmt.Println(" Answer: How many measurements are larger than the previous measurement?")
 
 	input, err := os.Open("./input.txt")
-	defer input.Close()
 	check(err)
+	defer input.Close()
 
 	scanner := bufio.NewScanner(input)
 
@@ -67,8 +67,8 @@ func part2() {
 	fmt.Println(" Answer: How many sums are larger than the previous sum?")
 
 	input, err := os.Open("./input.txt")
-	defer input.Close()
 	check(err)
+	defer input.Close()
 
 	scanner := bufio.NewScanner(input)
 

day-1/main_test.go

@@ -1,14 +1,14 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 
 func TestPrintPip(t *testing.T) {
 	DEBUG = false
 	str := GetPip(1, 1, 1, 100)
-	assert.StrEquals(t, str, "", "Should return an empty string")
+	assert.EqualsStr(t, str, "", "Should return an empty string")
 
 	DEBUG = true
 	cases := []struct {
@@ -24,7 +24,7 @@ func TestPrintPip(t *testing.T) {
 
 	for _, c := range cases {
 		str := GetPip(c.first, c.previous, c.current, c.total)
-		assert.StrEquals(t, str, c.expected, c.msg)
+		assert.EqualsStr(t, str, c.expected, c.msg)
 	}
 
 }

day-2/main_test.go

@@ -1,11 +1,11 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 
 func TestDay2(t *testing.T) {
 	assert.IsTrue(t, true, "cool")
-	assert.StrEquals(t, "foo", "bar", "baz")
+	assert.EqualsStr(t, "foo", "bar", "baz")
 }

day-3/main_test.go

@@ -1,11 +1,11 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 
 func TestDay3(t *testing.T) {
 	assert.IsTrue(t, true, "cool")
-	assert.StrEquals(t, "foo", "bar", "baz")
+	assert.EqualsStr(t, "foo", "bar", "baz")
 }

day-4/main_test.go

@@ -1,11 +1,11 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 
 func TestDay4(t *testing.T) {
 	assert.IsTrue(t, true, "cool")
-	assert.StrEquals(t, "foo", "bar", "baz")
+	assert.EqualsStr(t, "foo", "bar", "baz")
 }

day-6/main_test.go

@@ -1,11 +1,11 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 
 func TestDay6(t *testing.T) {
 	assert.IsTrue(t, true, "cool")
-	assert.StrEquals(t, "foo", "bar", "baz")
+	assert.EqualsStr(t, "foo", "bar", "baz")
 }

day-7/main_test.go

@@ -1,11 +1,11 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 
 func TestDay7(t *testing.T) {
 	assert.IsTrue(t, true, "cool")
-	assert.StrEquals(t, "foo", "bar", "baz")
+	assert.EqualsStr(t, "foo", "bar", "baz")
 }

day-8/main.go

@@ -0,0 +1,232 @@
+/* Day 8: Seven Segment Search */
+package main
+
+import (
+	"AoC2021/utils/arrays"
+	"AoC2021/utils/bits"
+	"AoC2021/utils/log"
+	"AoC2021/utils/timer"
+	"bufio"
+	"math"
+	"os"
+	"strings"
+)
+
+func check(e error) {
+	if e != nil {
+		log.Println(log.DEBUG, "Oh snap!")
+		panic(e)
+	}
+}
+
+func main() {
+	log.Println(log.NORMAL, "--- Day 8: Seven Segment Search ---")
+	timer.Start()
+	part1()
+	timer.Tick()
+	log.Println(log.NORMAL)
+
+	part2()
+	timer.Tick()
+	log.Println(log.NORMAL)
+}
+
+func part1() {
+	log.Println(log.NORMAL, "* Part 1 *")
+	log.Println(log.NORMAL, " Goal: For now, focus on the easy digits.")
+	log.Println(log.NORMAL, " Answer: In the output values, how many times do digits 1, 4, 7, or 8 appear?")
+
+	input, err := os.Open("./input.txt")
+	check(err)
+	defer input.Close()
+
+	scanner := bufio.NewScanner(input)
+	lines := 0
+	ones := 0
+	fours := 0
+	sevens := 0
+	eights := 0
+
+	for scanner.Scan() {
+		fields := strings.Split(scanner.Text(), " | ")
+		if len(fields) != 2 {
+			panic("Read invalid input line")
+		}
+		_ = strings.Fields(fields[0])
+		// count all the ones, fours, sevens, and eights in the output strings based on how many segments are lit up
+		outputDigits := strings.Fields(fields[1])
+		for _, d := range outputDigits {
+			switch len(d) {
+			case 2:
+				ones += 1
+			case 3:
+				sevens += 1
+			case 4:
+				fours += 1
+			case 7:
+				eights += 1
+			}
+		}
+		lines++
+	}
+
+	total := ones + fours + sevens + eights
+	log.Printf(log.NORMAL, "Read %d lines from input\n", lines)
+	log.Printf(log.NORMAL, "We counted %d ones, %d fours, %d sevens, and %d eights for a total of %d\n", ones, fours, sevens, eights, total)
+}
+
+func part2() {
+	log.Println(log.NORMAL, "* Part 2 *")
+	log.Println(log.NORMAL, " Goal: For each entry, determine all of the wire/segment connections and decode the four-digit output values")
+	log.Println(log.NORMAL, " Answer: What do you get if you add up all of the output values?")
+
+	input, err := os.Open("./input.txt")
+	check(err)
+	defer input.Close()
+
+	scanner := bufio.NewScanner(input)
+	lines := 0
+	total := 0
+
+	for scanner.Scan() {
+		fields := strings.Split(scanner.Text(), " | ")
+		if len(fields) != 2 {
+			panic("Read invalid input line")
+		}
+		inputFields := strings.Fields(fields[0])
+		segMap := createPatternMap(arrays.MapStrToInt(inputFields, ParseField))
+		log.Println(log.DEBUG, "Created pattern", segMap)
+
+		outputFields := strings.Fields(fields[1])
+
+		fieldValue := 0
+		fieldsCount := len(outputFields)
+		for idx, field := range outputFields {
+			fValue := segMap[ParseField(field)]
+			log.Printf(log.DIAGNOSTIC, "field %s => %d; ", field, fValue)
+			fieldValue += fValue * int(math.Pow10(fieldsCount-idx-1))
+		}
+		total += fieldValue
+
+		log.Println(log.DIAGNOSTIC)
+		log.Printf(log.DIAGNOSTIC, "Unscrambled %s => %d\n", outputFields, fieldValue)
+		lines++
+	}
+
+	log.Printf(log.NORMAL, "Read %d lines from input\n", lines)
+	log.Printf(log.NORMAL, "Calculated total is %d\n", total)
+}
+
+// Represent a segment as a 7-bit value
+/* Segment values are aligned as below
+*   aaaa
+*  b    c
+*  b    c
+*   dddd
+*  e    f
+*  e    f
+*   gggg
+
+* segment 'a' is found in [0, 2, 3, 5, 6, 7, 8, 9]    but not [1, 4]
+* segment 'b' is found in [0, 4, 5, 6, 8, 9]          but not [1, 2, 3, 7]
+* segment 'c' is found in [0, 1, 2, 3, 4, 7, 8, 9]    but not [5, 6]
+* segment 'd' is found in [2, 3, 4, 5, 6, 8, 9]       but not [0, 1, 7]
+* segment 'e' is found in [0, 2, 6, 8]                but not [1, 3, 4, 5, 7, 9]
+* segment 'f' is found in [0, 1, 3, 4, 5, 6, 7, 8, 9] but not [2]
+* segment 'g' is found in [0, 2, 3, 5, 6, 8, 9]       but not [1, 4, 7]
+ */
+
+// parse a field from a string value to a bit-map int value (eg 'cda' to b1101 => 13)
+func ParseField(field string) int {
+	value := 0
+	for _, c := range field {
+		value += 1 << int(rune(c)-rune('a'))
+	}
+	return value
+}
+
+// func getDefaultMap() map[int]int {
+// 	return map[int]int{
+// 		ParseField("abcefg"):  0,
+// 		ParseField("cf"):      1,
+// 		ParseField("acdeg"):   2,
+// 		ParseField("acdfg"):   3,
+// 		ParseField("bcdf"):    4,
+// 		ParseField("abdfg"):   5,
+// 		ParseField("abdefg"):  6,
+// 		ParseField("acf"):     7,
+// 		ParseField("abcdefg"): 8,
+// 		ParseField("abcdfg"):  9}
+// }
+
+// Given a list of a all 10 possible 7-segment displays create a map that can be used to unscramble values
+func createPatternMap(input []int) map[int]int {
+	// initialize our translation map that will convert from character to character (eg wire 'a' actually goes to segment 'c')
+	segMap := make(map[int]int)
+
+	// first find and map all the values that can be known by counting segments
+	// find the only pattern that matches '1'
+	one := arrays.FindFirstInt(input, bits.ByBitCount(2))
+
+	// next find the one that matches '7'
+	seven := arrays.FindFirstInt(input, bits.ByBitCount(3))
+
+	// next find the one that matches '4'
+	four := arrays.FindFirstInt(input, bits.ByBitCount(4))
+
+	// the one that matches '8' will be the only one with 7 segments but tells us nothing about what those segments map to
+	eight := arrays.FindFirstInt(input, bits.ByBitCount(7))
+
+	// the two segments in '1' will match 'c' or 'f' but we don't know yet
+	// the additional segment in '7' will map to segment 'a'
+	segMap['a'] = seven - one
+	// the two additional segments in '4' will match 'b' or 'd' but we're not sure which ones yet
+
+	// all of '0', '6' and '9' have 6 segments
+	// the six-segment field that shares only 1 side with '1' is '6'
+	six := arrays.FindFirstInt(input, func(v int) bool { return bits.ByBitCount(6)(v) && bits.MatchingOnBits(one, v) == 1 })
+
+	// and we know that the segment not in six is 'c'
+	segMap['c'] = eight - six
+	// and the other value 'f' will be the other segment in '1'
+	segMap['f'] = one - segMap['c']
+	// but we can't yet place '0' or '9' with what we know
+
+	// all of '2', '3', and '5' have 5 segments
+	// three is the only 5 segment field that matches 3 bits in '7'
+	three := arrays.FindFirstInt(input, func(v int) bool { return bits.ByBitCount(5)(v) && bits.MatchingOnBits(seven, v) == 3 })
+	// the additional two segments are 'd' ang 'g' but we can't place them yet
+	// five is the other 5 segment field that matches 3 bits in '4'
+	five := arrays.FindFirstInt(input, func(v int) bool { return bits.ByBitCount(5)(v) && v != three && bits.MatchingOnBits(four, v) == 3 })
+	// segments 'b', 'd', and 'g' can't yet be placed
+	// but segment 'e' is what we get by subtracting five from six
+	segMap['e'] = six - five
+
+	// the last five segment number must be 2
+	two := arrays.FindFirstInt(input, func(v int) bool { return bits.ByBitCount(5)(v) && v != three && v != five })
+
+	// segment 'g' is the only one that doesn't appear in '1', '4', or '7' and is not 'e'
+	segMap['g'] = eight - bits.BitwiseAndA(one, four, seven, segMap['e'])
+	// segment 'd' is '3' minus 'a', 'c', 'f', and 'g'
+	segMap['d'] = three - segMap['a'] - segMap['c'] - segMap['f'] - segMap['g']
+
+	// then we know that zero is eight minus 'd'
+	zero := eight - segMap['d']
+	// and nine will be eight minus 'e'
+	nine := eight - segMap['e']
+
+	log.Println(log.DIAGNOSTIC, "segMap", segMap)
+
+	return map[int]int{
+		zero:  0,
+		one:   1,
+		two:   2,
+		three: 3,
+		four:  4,
+		five:  5,
+		six:   6,
+		seven: 7,
+		eight: 8,
+		nine:  9,
+	}
+}

day-8/main_test.go

@@ -0,0 +1,10 @@
+package main
+
+import (
+	"AoC2021/utils/assert"
+	"testing"
+)
+
+func TestDay8ParseField(t *testing.T) {
+	assert.EqualsInt(t, ParseField("abc"), 7, "should parse fields correctly")
+}

main_test.go.template

@@ -1,7 +1,7 @@
 package main
 
 import (
-	assert "AoC2021/utils/testing"
+	"AoC2021/utils/assert"
 	"testing"
 )
 

makefile

@@ -11,4 +11,7 @@ build:
 	cd day-$(day); go run .
 
 test:
-	cd day-$(day); go test
+	cd day-$(day); go test
+
+test-utils:
+	go test ./utils/*

utils/arrays/arrays.go

@@ -0,0 +1,49 @@
+package arrays
+
+func FindFirst(list []string, filter func(string) bool) string {
+	for _, item := range list {
+		if filter(item) {
+			return item
+		}
+	}
+	panic("No item found that matches criteria")
+}
+
+func FindFirstInt(list []int, filter func(int) bool) int {
+	for _, item := range list {
+		if filter(item) {
+			return item
+		}
+	}
+	panic("No item found that matches criteria")
+}
+
+func FindAll(list []string, filter func(string) bool) []string {
+	var filteredList []string
+	for _, item := range list {
+		if filter(item) {
+			filteredList = append(filteredList, item)
+		}
+	}
+
+	return filteredList
+}
+
+func FindAllInt(list []int, filter func(int) bool) []int {
+	var filteredList []int
+	for _, item := range list {
+		if filter(item) {
+			filteredList = append(filteredList, item)
+		}
+	}
+
+	return filteredList
+}
+
+func MapStrToInt(input []string, fn func(string) int) []int {
+	var retVals []int
+	for _, s := range input {
+		retVals = append(retVals, fn(s))
+	}
+	return retVals
+}

utils/arrays/arrays_test.go

@@ -0,0 +1,47 @@
+package arrays
+
+import (
+	"AoC2021/utils/assert"
+	"testing"
+)
+
+func TestFindFirst(t *testing.T) {
+	list := []string{"foo", "bar", "baz"}
+	filter := func(s string) bool { return s == "baz" }
+	item := FindFirst(list, filter)
+
+	assert.EqualsStr(t, item, "baz", "should find item baz")
+}
+
+func TestFindFirstInt(t *testing.T) {
+	list := []int{1, 3, 4, 5}
+	filter := func(i int) bool { return i%2 == 0 }
+	item := FindFirstInt(list, filter)
+
+	assert.EqualsInt(t, item, 4, "should find even number")
+}
+
+func TestFindAll(t *testing.T) {
+	list := []string{"hello", "world", "foo"}
+	filter := func(s string) bool { return len(s) > 3 }
+	items := FindAll(list, filter)
+
+	assert.EqualsInt(t, len(items), 2, "should filter lists of strings")
+}
+
+func TestFindAllInt(t *testing.T) {
+	list := []int{1, 3, 99, 200, 9000}
+	filter := func(i int) bool { return i > 50 }
+	items := FindAllInt(list, filter)
+
+	assert.EqualsInt(t, len(items), 3, "should filter lists of ints")
+}
+
+func TestMapStrToInt(t *testing.T) {
+	list := []string{"alice", "bob", "carol"}
+	mapFn := func(s string) int { return int(s[0]) }
+
+	items := MapStrToInt(list, mapFn)
+
+	assert.EqualsInt(t, items[0], int('a'), "should run map function across all strings")
+}

utils/assert/assert.go

@@ -9,9 +9,16 @@ func IsTrue(t *testing.T, expr bool, message string) {
 	}
 }
 
-func StrEquals(t *testing.T, actual, expected, message string) {
+func EqualsStr(t *testing.T, actual, expected, message string) {
 	if actual != expected {
 		t.Logf("Expected value '%s' but got '%s': %s", expected, actual, message)
 		t.Fail()
 	}
 }
+
+func EqualsInt(t *testing.T, actual, expected int, message string) {
+	if actual != expected {
+		t.Logf("Expected value '%d' but got '%d': %s", expected, actual, message)
+		t.Fail()
+	}
+}

utils/bits/bits.go

@@ -0,0 +1,54 @@
+package bits
+
+func GetBitCount(val int) int {
+	count := 0
+	for val != 0 {
+		count += val & 1
+		val >>= 1
+	}
+
+	return count
+}
+
+// returns the number of matching bits in the two value's binary expression
+func MatchingOnBits(v1 int, v2 int) int {
+	count := 0
+	for v1 != 0 && v2 != 0 {
+		if v1&1 == 1 && v2&1 == 1 {
+			count += 1
+		}
+		v1 >>= 1
+		v2 >>= 1
+	}
+
+	return count
+}
+
+func BitwiseAnd(v1 int, v2 int) int {
+	val := 0
+	for block := 1; v1 != 0 || v2 != 0; block <<= 1 {
+		if v1&1 == 1 || v2&1 == 1 {
+			val += block
+		}
+		if v1 > 0 {
+			v1 >>= 1
+		}
+		if v2 > 0 {
+			v2 >>= 1
+		}
+	}
+	return val
+}
+
+func BitwiseAndA(a ...int) int {
+	total := 0
+	for _, i := range a {
+		total = BitwiseAnd(total, i)
+	}
+
+	return total
+}
+
+func ByBitCount(size int) func(int) bool {
+	return func(val int) bool { return GetBitCount(val) == size }
+}

utils/bits/bits_test.go

@@ -0,0 +1,28 @@
+package bits
+
+import (
+	"AoC2021/utils/assert"
+	"testing"
+)
+
+func TestGetBitCount(t *testing.T) {
+	assert.EqualsInt(t, GetBitCount(0), 0, "should count zero bits")
+	assert.EqualsInt(t, GetBitCount(15), 4, "should count bits")
+	assert.EqualsInt(t, GetBitCount(16), 1, "should not count empty bits")
+}
+func TestMatchingOnBits(t *testing.T) {
+	assert.EqualsInt(t, MatchingOnBits(5 /*101*/, 13 /*1101*/), 2, "should match 2 bits")
+}
+
+func TestBitwiseAnd(t *testing.T) {
+	assert.EqualsInt(t, BitwiseAnd(7 /*111*/, 18 /*10010*/), 23 /*10111*/, "should bitwise add")
+}
+
+func TestBitwiseAndA(t *testing.T) {
+	assert.EqualsInt(t, BitwiseAndA(1, 4, 8, 12), 13 /*1101*/, "should bitwise add lists")
+}
+
+func TestByBitCount(t *testing.T) {
+	twoBitFilter := ByBitCount(2)
+	assert.IsTrue(t, twoBitFilter(17 /*10001*/), "should count bits")
+}

utils/filters/filters.go

@@ -0,0 +1,5 @@
+package filters
+
+func ByLength(size int) func(string) bool {
+	return func(val string) bool { return len(val) == size }
+}

utils/log/log.go

@@ -3,9 +3,10 @@ package log
 import "fmt"
 
 const (
-	NONE   = 0
-	NORMAL = 1
-	DEBUG  = 2
+	NONE       = 0
+	NORMAL     = 1
+	DEBUG      = 2
+	DIAGNOSTIC = 3
 )
 
 var LOG_LEVEL = NORMAL