On Thu, Jun 08, 2017 at 04:03:55PM +0300, Mahmoud Murad wrote:
I have the following problem, I want to randomly generate arithmetic expressions based on a number, for example: if I have n = 3, then the expression must have 3 operators like this (4)*(((3+5)-2)).
I don't seem to have the original message in my mailbox, so my response may be inappropriate. Generating random arithmetic expressions in Haskell has two parts: how to generate random arithmetic expressions at all, and how to do it in Haskell. Assuming that "arithmetic expressions" means expressions using numbers and the four binary operations + - * / (or possibly the exponentiation operator as well), the basic problem reduces to * generate a random binary tree with n internal nodes * assign random numbers to the leaves * assign random operators to the internal nodes The last two subtasks are pretty easy. This leaves generating random binary trees as the main problem. This paper may help: http://www.cs.otago.ac.nz/staffpriv/mike/Papers/RandomGeneration/RandomBinar... There's a survey paper at http://www.sis.uta.fi/cs/reports/A-1998-3.ps.Z and the Atkinson/Sack approach does seem to be pretty good, at least if you want to make *large* expressions. This only matters if you want all expressions to be equally likely. You may not.