Can I smoke in public places in Singapore?

I [M20] am travelling to Singapore from India and was looking at rules regarding smoking and vaping, vapes are banned and purchasing cigarettes under the age of 21 is illegal, however would it be okay if i carry a few packs of my own? Would they ask me about my age or will I be stopped for bringing cigarettes from a different country? Also can I just smoke on the street or would i need to go to specific locations to smoke?