Solve p17 in fortran

README.rst

@@ -87,7 +87,7 @@ Olivia's Project Euler Solutions
    |            |                            |        | |CodeQL| |br|     |
    |            |                            |        | |C#-lint|         |
    +------------+----------------------------+--------+-------------------+
-   | Fortran    | Fortran 95+                |  8     | |Fri|             |
+   | Fortran    | Fortran 95+                |  9     | |Fri|             |
    +------------+----------------------------+--------+-------------------+
    | Java       | Java 8+ in Corretto, |br|  | 22     | |Javai| |br|      |
    |            | Dragonwell, Liberica, |br| |        | |Ja-Cov| |br|     |

docs/index.rst

@@ -110,7 +110,7 @@ Problems Solved
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+------------+
   |:prob:`016`|:c-d:`0016`|:cp-d:`0016`|:cs-d:`0016`|            |:ja-d:`0016`|:js-d:`0016`|            |:py-d:`0016`|:rs-d:`0016`|
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+------------+
-  |:prob:`017`|:c-d:`0017`|:cp-d:`0017`|:cs-d:`0017`|            |:ja-d:`0017`|:js-d:`0017`|:lu-d:`0017`|:py-d:`0017`|:rs-d:`0017`|
+  |:prob:`017`|:c-d:`0017`|:cp-d:`0017`|:cs-d:`0017`|:fr-d:`0017`|:ja-d:`0017`|:js-d:`0017`|:lu-d:`0017`|:py-d:`0017`|:rs-d:`0017`|
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+------------+
   |:prob:`018`|           |            |            |            |            |:js-d:`0018`|            |:py-d:`0018`|:rs-d:`0018`|
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+------------+

docs/src/fortran/p0017.rst

@@ -0,0 +1,14 @@
+Fortran Implementation of Problem 17
+====================================
+
+View source code :source:`fortran/src/p0017.f90`
+
+.. f:module:: Problem0017
+
+.. f:function:: integer Problem0017/p0017()
+
+.. literalinclude:: ../../../fortran/src/p0017.f90
+   :language: Fortran
+   :linenos:
+
+.. tags:: word-problem, combinatorics

fortran/README.rst

@@ -66,4 +66,5 @@ Problems Solved
 -  ☒ `9 <./src/p0009.f95>`__
 -  ☒ `11 <./src/p0011.f95>`__
 -  ☒ `13 <./src/p0013.f95>`__
+-  ☒ `17 <./src/p0017.f95>`__
 -  ☒ `836 <./src/p0836.f95>`__

fortran/src/p0017.f90

@@ -0,0 +1,77 @@
+! Project Euler Problem 17
+!
+! The key here was remembering I don't need to return the whole string, just the length
+!
+! Problem:
+!
+! If the numbers 1 to 5 are written out in words: one, two, three, four, five,
+! then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
+!
+! If all the numbers from 1 to 1000 (one thousand) inclusive were written out in
+! words, how many letters would be used?
+!
+! NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and
+! forty-two) contains 23 letters and 115 (one hundred and fifteen) contains 20
+! letters. The use of "and" when writing out numbers is in compliance with
+! British usage.
+
+module Problem0017
+    implicit none
+contains
+    integer recursive function to_string_len(n) result(answer)
+        integer, intent(in) :: n, tmp
+        if (n >= 1000) then
+            answer = to_string_len(n / 1000 % 100) + 8
+            if (n % 1000 /= 0) then
+                answer = answer + to_string_len(n % 1000)
+            end if
+
+        elseif (n >= 100) then
+            answer = to_string_len(n / 100 % 10) + 7
+            if (n % 100 /= 0) then
+                answer = answer + 3 + to_string_len(n % 100)
+            end if
+
+        elseif (n >= 20) then
+            select case (n / 10)
+                case (4, 5, 6)
+                    answer = 5
+                case (2, 3, 8, 9)
+                    answer = 6
+                case (7)
+                    answer = 7
+            end select
+
+            if (n % 10 /= 0) then
+                answer = answer + to_string_len(n % 10)
+            end if
+
+        else
+            select case (n)
+                case (1, 2, 6, 10)
+                    answer = 3
+                case (0, 4, 5, 9)
+                    answer = 4
+                case (3, 7, 8)
+                    answer = 5
+                case (11, 12)
+                    answer = 6
+                case (15, 16)
+                    answer = 7
+                case (13, 14, 18, 19)
+                    answer = 8
+                case (17)
+                    answer = 9
+            end select
+        end if
+    end function
+
+    integer function p0017() result(answer)
+        integer :: x
+
+        answer = 0
+        do x = 1, 1000
+            answer = answer + to_string_len(x)
+        end do
+    end function p0017
+end module Problem0017

fortran/test.f90

@@ -8,14 +8,15 @@ program test
     use Problem0009
     use Problem0011
     use Problem0013
+    use Problem0017
     use Problem0836
 
     implicit none
     integer(i4t), dimension(:), allocatable :: problem_ids
     logical, dimension(:), allocatable :: long_runtime
     integer :: num_problems
 
-    num_problems = 8
+    num_problems = 9
     allocate(problem_ids(num_problems))
     allocate(long_runtime(num_problems))
     if (.not. (allocated(problem_ids) .and. allocated(long_runtime))) then
@@ -30,6 +31,7 @@ program test
         009_i4t, &
         011_i4t, &
         013_i4t, &
+        017_i4t, &
         836_i4t &
     /)
     long_runtime = (/ &
@@ -40,6 +42,7 @@ program test
         .false., &
         .false., &
         .false., &
+        .false., &
         .false. &
     /)
 
@@ -137,6 +140,8 @@ type(AnswerT) function select_function(problem_id) result(answer)
                 answer%int_value = p0011()
             case (13)
                 answer%int_value = p0013()
+            case (17)
+                answer%int_value = p0017()
             case (836)
                 allocate(character(len=14) :: answer%string_value)
                 if (.not. allocated(answer%string_value)) then