https://medium.com/@mehmetakgul.developer/string-perm%C3%BCtasyonlar%C4%B1n%C4%B1n-big-o-karma%C5%9F%C4%B1kl%C4%B1%C4%9F%C4%B1-detayl%C4%B1-bir-i%CC%87nceleme-ve-uygulama-726de852805