I like BTP-Sort. It’s O(n). Really easy: you see it, then you say it, then it’s sorted. https://www.btp.police.uk/police-forces/british-transport-police/areas

I like BTP-Sort. It’s O(n). Really easy: you see it, then you say it, then it’s sorted. https://www.btp.police.uk/police-forces/british-transport-police/areas/campaigns/see-it-say-it-sorted/ https://www.btp.police.uk/police-forces/british-transport-po... (this is a famous national campaign on the British railways over the past few years)