Looking for an algorithm to spit out a sequence of numbers in a (pseudo) random order

Question

Suppose I have a sequence of numbers: {n, n+1, n+2, ... n + m}

Without storing the numbers ahead of time I want to create a function f(), which given the sequence {1,2,3

Answer 1

If you want a 1:1 mapping, go with Fisher-Yates as mentioned in the other answers.

If you don't care about 1:1 mapping, and you just need all of the resulting values to be from the given sequence (with the possibility of repeats), then you can use a random function with a specified range.

For example, in C++, you could use rand() in the following way -

result = rand() % (m+1) + n

So for your example,

result = rand() % 8 + 10

Would produce an integer between 10 and 17.