# project-euler

committed bcb814f

Get a little closer to an answer.

# OCaml/Euler023.ml

` `
` module Euler023 : sig`
`   val is_abundant : int -> bool`
`+  val solution : unit -> int list`
` end = struct`
`   let sum l = List.fold_right (fun (n, m) b -> n + m + b) l 0`
`   let is_abundant n =`
`     else`
`       sum (TaylorNumber.factors n) > n`
`   let solution () =`
`-    List.filter (not <<- is_abundant) (TaylorList.iota 1 28123);;`
`-end`
`+    let a_list = List.filter (not <<- is_abundant) (TaylorList.iota 1 28123) in`
`+    let a_nums = Array.make 28124 0 in`
`+    (* Return true when expressible as sum of abundant numbers. *)`
`+    let expressible n =`
`+      let rec check' start =`
`+        let i = ref start in`
`+        while !i < Array.length a_nums && a_nums.(!i) != 0 do`
`+          i := !i + 1`
`+        done;`
`+        if !i == Array.length a_nums || n < !i || n > !i then`
`+          false`
`+        else`
`+          if a_nums.(n - !i) == 1 then true else check' (!i + 1)`
`+      in`
`+      check' 1`
`+    in`
`+    (* Set values in the array according to the list. *)`
`+    List.iter (fun n -> a_nums.(n) <- 1) a_list;`
`+    List.filter (not <<- expressible) (TaylorList.iota 1 (2 * 28123))`
`+end;;`
`+`
`+print_string "Solution = ";`
`+print_int (List.fold_left (+) 0 (Euler023.solution ()))`
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