Problem 34

The solution for this problem is somewhat similar to the 30th problem, as it involves the construction of a list based on the problem rules:

    import Char

    f = sum [x | x <- [3..50000], x == g x]
      where g = sum .
                map (factorial . digitToInt) .
                show
            factorial n = foldl (*) 1 [1..n]

    main = print f

Again, the execution was quite fast:

real 0m0.059s user 0m0.056s sys 0m0.003s

However, I started with going until 10^6, since I din’t know how many numbers would satisfy the condition. In fact, there are only two, so I could therefore reduce the search domain considerably.