// Package isogram is for determining if a word/phrase is an isogram.
package isogram
import (
	"strings"
)
// IsIsogram returns true if input is an isogram, false otherwise.
func IsIsogram(input string) (ret bool) {
	// Space, hyphen and mixed case does not matter
	input = strings.ReplaceAll(input, " ", "")
	input = strings.ReplaceAll(input, "-", "")
	input = strings.ToLower(input)
	// Preallocate worst case map size, this way there is no need to reallocate
	// This make the code ~40-60% faster with these short words
	used := make(map[rune]bool, len(input))
	for _, ch := range input {
		if _, found := used[ch]; found {
			// this rune is already in the map
			return false
		}
		used[ch] = true
	}
	return true
}