advent-of-code/itertools.go

package aoc

import (
	"iter"
	"strconv"
)

func Atoi(s string) int {
	i, _ := strconv.Atoi(s)
	return i
}

func Repeat[T any](s T, i int) []T {
	lis := make([]T, i)
	for i := range lis {
		lis[i] = s
	}
	return lis
}

func Reduce[T, U any](fn func(int, T, U) U, u U, list iter.Seq[T]) U {
	for i, t := range Enumerate(list) {
		u = fn(i, t, u)
	}
	return u
}

func Reverse[T any](arr []T) []T {
	for i := 0; i < len(arr)/2; i++ {
		arr[i], arr[len(arr)-i-1] = arr[len(arr)-i-1], arr[i]
	}
	return arr
}

func SliceMap[T, U any](fn func(T) U, in ...T) []U {
	lis := make([]U, len(in))
	for i := range lis {
		lis[i] = fn(in[i])
	}
	return lis
}
func SliceIMap[T, U any](fn func(int, T) U, in ...T) []U {
	lis := make([]U, len(in))
	for i := range lis {
		lis[i] = fn(i, in[i])
	}
	return lis
}

// Pairwise iterates over a list pairing i, i+1
func Pairwise[T any](arr []T) [][2]T {
	var pairs [][2]T
	for i := range arr[:len(arr)-1] {
		pairs = append(pairs, [2]T{arr[i], arr[i+1]})
	}
	return pairs
}

func Enumerate[T any](arr iter.Seq[T]) iter.Seq2[int, T] {
	return func(yield func(int, T) bool) {
		i := 0
		for v := range arr {
			if !yield(i, v) {
				return
			}
		}
	}
}