URL

Combination Sum - LeetCode

Code

https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/problems/0039/main.fsx

let combinationSum (nums: int list) (target: int) : int list list =
    let rec combinationSum' i (nums: int list) target ys ret =
        let sum = ys |> List.sum
        if sum = target then
            (List.rev ys) :: ret
        else if sum > target || i >= (List.length nums) then
            ret
        else
            nums
            |> List.mapi (fun i num -> (i, num))
            |> List.skip i
            |> List.fold (fun acc (i, num) -> combinationSum' i nums target (num :: ys) acc) ret
    combinationSum' 0 (nums |> List.sort) target [] []
    |> List.rev