Assuming the human race goes crazy and kill each other out of desparation, I should be safe. 9 years of martial arts and weaponary training will finally be of use. And as for guns/bows, Impossible to get one in singapore unless you are with the defense force. So...most they'll have are knives. Which I can easily deal with.
Food and water wont be a problem. Its everywhere. I can just steal some anytime I need. And besides, I have about 50 cans of food expiring in 2015 at home and about 40 bottles of water.
Nothing is impossible to get... You'd be surprised how many people in your area (or nearest city) have some form of firearm. Plus your attitude of 'all they'd have are knives, which i can easily deal with' and 'i can just steal some anytime i need' won't do you any favors if a SHTF situation arrises. Hopefully you weren't being serious with that post though.