General Tips

General Tips

• Avoid off by one errors

• Random Numbers

Avoid off by one errors

Just solve with small numbers and the addition / subtraction gives you clue towards if you need to add / remove a +1.

Random Numbers

You can get random number in O(1) (for asymptomatic analysis). Operating systems generally have an entropy pool (using user input / cpu usage etc) that they provide to programs that need them (either natively or through the virtual machine of your language).

JavaScript Math.random provides you with a random floating point number between range [0, 1). To get an integer just use the following function:

function getRandom(floor:number, ceiling:number) {
    return Math.floor(Math.random() * (ceiling - floor + 1)) + floor;
}

+ floor ensures its at least floor and then we just generate a random number between [ 0 -- (ceiling - floor + 1) ).

Math.random is pseudo-random but good enough for most cases. For true randomness (entropy pool version) and security critical applications you need something like NodeJS crypto.