What are some ways to stop smokers from smoking in public bathrooms?

I think fines are the most effective method. Public places do not belong to one person. Knowing clearly that smoking is harmful to health and still insisting on smoking shows that these smokers will not change just by preaching. Post a notice stating that smoking in public bathrooms is fined 50 RMB, and patrols are set up to support reporting. Once or twice fined, they will remember it and will soon put an end to this phenomenon.