Day_1

2023/gareth/utils/utils.go

@@ -0,0 +1,207 @@
+package utils
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"golang.org/x/exp/constraints"
+)
+
+func PanicOnErr(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+const MaxInt = int(^uint(0) >> 1)
+const MinInt = ^MaxInt
+
+func Max[T constraints.Ordered](a, b T) T {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func Min[T constraints.Ordered](a, b T) T {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func SliceMinMax[T constraints.Ordered](slice []T) (*T, *T) {
+	if len(slice) == 0 {
+		return nil, nil
+	}
+	min := &slice[0]
+	max := &slice[0]
+	for i, v := range slice {
+		if v < *min {
+			min = &slice[i]
+		}
+		if v > *max {
+			max = &slice[i]
+		}
+	}
+	return min, max
+}
+
+func MustAtoi(s string) int {
+	v, err := strconv.Atoi(s)
+	PanicOnErr(err)
+	return v
+}
+
+// Returns key from map[T]int which has the max value
+func MapFindMax(m interface{}) interface{} {
+	var maxK interface{} = nil
+	var maxV = MinInt
+	iter := reflect.ValueOf(m).MapRange()
+	for iter.Next() {
+		k := iter.Key()
+		v := int(iter.Value().Int())
+		if v > maxV {
+			maxV = v
+			maxK = k.Interface()
+		}
+	}
+	return maxK
+}
+
+// Returns key from map[T]int which has the min value
+func MapFindMin(m interface{}) interface{} {
+	var minK interface{} = nil
+	var minV = MaxInt
+	iter := reflect.ValueOf(m).MapRange()
+	for iter.Next() {
+		k := iter.Key()
+		v := int(iter.Value().Int())
+		if v < minV {
+			minV = v
+			minK = k.Interface()
+		}
+	}
+	return minK
+}
+
+func Readfile(day int) string {
+	filename := fmt.Sprintf("day%02d/input.txt", day)
+	file, err := os.Open(filename)
+	PanicOnErr(err)
+	defer file.Close()
+
+	reader := bufio.NewReader(file)
+	contents, err := io.ReadAll(reader)
+	PanicOnErr(err)
+
+	return strings.TrimSuffix(string(contents), "\n")
+}
+
+func ParseToStruct(re *regexp.Regexp, input string, target interface{}) bool {
+	m := re.FindStringSubmatch(input)
+	if m == nil {
+		return false
+	}
+
+	var useOffset bool
+
+	for i, name := range re.SubexpNames() {
+		if i == 0 {
+			continue
+		}
+		var field reflect.Value
+		if name == "" {
+			// use offset
+			if i == 1 {
+				useOffset = true
+			} else if !useOffset {
+				panic("can't mix named and unnamed subexpressions")
+			}
+			field = reflect.ValueOf(target).Elem().Field(i - 1)
+		} else {
+			// use name
+			if i == 1 {
+				useOffset = false
+			} else if useOffset {
+				panic("can't mix named and unnamed subexpressions")
+			}
+			field = reflect.ValueOf(target).Elem().FieldByName(name)
+		}
+		if field.Kind() == reflect.String {
+			field.SetString(m[i])
+		} else if field.Kind() == reflect.Int {
+			v, err := strconv.Atoi(m[i])
+			PanicOnErr(err)
+			field.SetInt(int64(v))
+		} else if field.Kind() == reflect.Uint8 {
+			if len(m[i]) != 1 {
+				panic(fmt.Sprintf("expecting 1 char, got: %s", m[i]))
+			}
+			field.SetUint(uint64(m[i][0]))
+		} else {
+			panic(fmt.Sprintf("unknown kind: %s", field.Kind()))
+		}
+	}
+	return true
+}
+
+func MustParseToStruct(re *regexp.Regexp, input string, target interface{}) {
+	if !ParseToStruct(re, input, target) {
+		panic(fmt.Errorf("failed to parse: %s", input))
+	}
+}
+
+func CharToLower(c byte) byte {
+	return strings.ToLower(string(c))[0]
+}
+
+func CharToUpper(c byte) byte {
+	return strings.ToUpper(string(c))[0]
+}
+
+func Contains(haystack []string, needle string) bool {
+	for _, s := range haystack {
+		if s == needle {
+			return true
+		}
+	}
+	return false
+}
+
+func Abs[T constraints.Signed](x T) T {
+	if x < 0 {
+		return -x
+	}
+	return x
+}
+
+func Gcd(x, y int) int {
+	if x <= 0 || y <= 0 {
+		panic(fmt.Errorf("invalid input: %d, %d", x, y))
+	}
+	if x == y {
+		return x
+	}
+	if x > y {
+		return Gcd(x-y, y)
+	} else {
+		return Gcd(x, y-x)
+	}
+}
+
+func Sign[T constraints.Signed](x T) int {
+	if x < 0 {
+		return -1
+	} else if x > 0 {
+		return 1
+	} else {
+		return 0
+	}
+}