An interview question: About Probability

Question

An interview question:

Given a function f(x) that 1/4 times returns 0, 3/4 times returns 1. Write a function g(x) using f(x) that 1/2 times returns 0, 1/2 times returns

Answer 1

As already mentioned your definition is not that good regarding probability. Usually it means that not only probability is good but distribution also. Otherwise you can simply write g(x) which will return 1,0,1,0,1,0,1,0 - it will return them 50/50, but numbers won't be random.

Another cheating approach might be:

var invert = false;
function g(x) {
    invert = !invert;
    if (invert) return 1-f(x);
    return f(x);
}

This solution will be better than all others since it calls f(x) only one time. But the results will not be very random.