aoc2023/utils/utils.go

package utils

import (
	"bufio"
	"log"
	"os"
	"strconv"
	"strings"
)

func ReadLines(fileName string) []string {
	result := []string{}
	file, err := os.Open(fileName)
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		result = append(result, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}

	return result
}

func ParseIntArray(s string, sep string) []int {
	result := []int{}

	var vals []string
	if sep == " " {
		vals = strings.Fields(strings.TrimSpace(s))
	} else {
		vals = strings.Split(strings.TrimSpace(s), sep)
	}

	for _, val := range vals {
		n, _ := strconv.Atoi(val)
		result = append(result, n)
	}

	return result
}

func ParseInt64Array(s string, sep string) []int64 {
	result := []int64{}

	var vals []string
	if sep == " " {
		vals = strings.Fields(strings.TrimSpace(s))
	} else {
		vals = strings.Split(strings.TrimSpace(s), sep)
	}

	for _, val := range vals {
		n, _ := strconv.ParseInt(val, 10, 64)
		result = append(result, n)
	}

	return result
}

func IntPow(x int, y int) int {
	result := 1

	for i := 0; i < y; i++ {
		result *= x
	}

	return result
}

func Int64Pow(x int64, y int64) int64 {
	result := int64(1)

	for i := int64(0); i < y; i++ {
		result *= x
	}

	return result
}

func Pow2(x int) int {
	return 1 << x
}

// greatest common divisor (GCD) via Euclidean algorithm
func GCD(a, b int) int {
	for b != 0 {
		t := b
		b = a % b
		a = t
	}
	return a
}

// find Least Common Multiple (LCM) via GCD
func LCM(a, b int, integers ...int) int {
	result := a * b / GCD(a, b)

	for i := 0; i < len(integers); i++ {
		result = LCM(result, integers[i])
	}

	return result
}

func Fold[A any, T any](a A, s []T, f func(A, T) A) A {
	for i := range s {
		a = f(a, s[i])
	}
	return a
}

func AbsInt(x int) int {
	if x >= 0 {
		return x
	} else {
		return -x
	}
}

func SplitNoBlank(s string, sep string) []string {
	splitted_line := strings.Split(s, sep)

	result := []string{}

	for _, part := range splitted_line {
		if part != "" {
			result = append(result, part)
		}
	}

	return result
}

func Transpose[T any](slice [][]T) [][]T {
	xl := len(slice[0])
	yl := len(slice)
	result := make([][]T, xl)
	for i := range result {
		result[i] = make([]T, yl)
	}
	for i := 0; i < xl; i++ {
		for j := 0; j < yl; j++ {
			result[i][j] = slice[j][i]
		}
	}
	return result
}

func RotateClockwise[T any](slice [][]T) [][]T {
	xl := len(slice[0])
	yl := len(slice)
	result := make([][]T, xl)
	for i := range result {
		result[i] = make([]T, yl)
	}

	/*
			r=0,c=0 -> c,width-1-r
		r=0,c=1 -> c,width-1


		r=1, c=0 -> c, width-1-r
	*/
	for row := 0; row < yl; row++ {
		for col := 0; col < xl; col++ {
			result[col][yl-1-row] = slice[row][col]
		}
	}
	return result
}

func Reduce[T, M any](s []T, initValue M, f func(M, T) M) M {
	acc := initValue
	for _, v := range s {
		acc = f(acc, v)
	}
	return acc
}

func Map[T, M any](s []T, f func(T) M) []M {
	res := []M{}
	for _, v := range s {
		res = append(res, f(v))
	}
	return res
}