From f6096218e4f86ec82801a9edc115877d5165ee06 Mon Sep 17 00:00:00 2001
From: Greg Burri <greg.burri@gmail.com>
Date: Tue, 4 Dec 2018 22:39:54 +0100
Subject: [PATCH] Day 4 , part 1.

---
 Day04.fs             | 47 +++++++++++++++++++++-----------------------
 Program.fs           |  6 +++---
 Tests/Day04 tests.fs |  2 +-
 3 files changed, 26 insertions(+), 29 deletions(-)

diff --git a/Day04.fs b/Day04.fs
index c3f2ee6..c56203d 100644
--- a/Day04.fs
+++ b/Day04.fs
@@ -1,18 +1,11 @@
 module AdventOfCode2018.Day04
 
 open System
+open System.Collections.Generic
 
-let parseInput (str : string) : string =
+let getSleepestGuard (str : string) : int * int =
     let shifts : int list array = Array.create 60 []
 
-    let addShift (id : int) (date1 : DateTime) (date2 : DateTime) =
-
-        let min1 = if date1.Hour > 0 then 0 else date1.Minute
-        let min2 = if date2.Hour > 0 then 59 else date2.Minute
-
-        for m = min1 to min2 - 1 do
-            shifts.[m] <- id :: shifts.[m]
-
     let lines =
         str.Split ([| '\r'; '\n'; |], StringSplitOptions.RemoveEmptyEntries)
         |> Array.choose (
@@ -21,15 +14,18 @@ let parseInput (str : string) : string =
                 if trimmed = "" then None else Some (DateTime.Parse (trimmed.Substring (1, 16)), trimmed)
         )
         |> Array.sortBy fst
-        (*
-        |> Array.fold (
-            fun id (dateTime, line) ->
-                match line.IndexOf '#' with
-                | i when i <> -1 -> line.Substring (i + 1, line.IndexOf (' ', i) - i - 1) |> int
-                | _ ->
-        ) 0*)
 
     let mutable id = 0
+    let minutesAsleep = Dictionary<int, int> ()
+
+    let addShift (date1 : DateTime) (date2 : DateTime) =
+        let min1 = if date1.Hour > 0 then 0 else date1.Minute
+        let min2 = if date2.Hour > 0 then 60 else date2.Minute
+
+        minutesAsleep.[id] <- minutesAsleep.GetValueOrDefault (id, 0) + min2 - min1
+
+        for m = min1 to min2 - 1 do
+            shifts.[m] <- id :: shifts.[m]
 
     for i = 0 to lines.Length - 1 do
         let dateTime, line = lines.[i]
@@ -37,17 +33,18 @@ let parseInput (str : string) : string =
         | i when i <> -1 -> id <- line.Substring (i + 1, line.IndexOf (' ', i) - i - 1) |> int
         | _ ->
             if line.Contains "wakes up" then
-                addShift id (fst lines.[i-1]) dateTime
-
-    sprintf "%A" shifts
-
-
-
-
+                addShift (fst lines.[i-1]) dateTime
 
+    let sleepestGuardId, _  = minutesAsleep |> Seq.fold (fun (id, max) guard -> if guard.Value > max then guard.Key, guard.Value else id, max) (0, 0)
 
+    let mutable sleepestTime = 0
+    let mutable asleepCountMax = 0
 
-    //Map<int, int>.
+    for i = 0 to shifts.Length - 1 do
+        let asleepCount = shifts.[i] |> List.where ((=) sleepestGuardId) |> List.length
+        if asleepCount > asleepCountMax then
+            sleepestTime <- i
+            asleepCountMax <- asleepCount
 
+    sleepestGuardId, sleepestTime
 
-    //
\ No newline at end of file
diff --git a/Program.fs b/Program.fs
index 346eb36..6e7f256 100644
--- a/Program.fs
+++ b/Program.fs
@@ -15,11 +15,11 @@ let day02 () =
 let day03 () =
     let claims = File.ReadAllText "Data/day03.input" |> Day03.parseInput
     let surface, claimId = Day03.overlappingSurface claims
-    sprintf "part1 = %A, part2 = %A"  surface claimId
+    sprintf "part1 = %A, part2 = %A" surface claimId
 
 let day04 () =
-    // sprintf "part1 = %A, part2 = %A"  surface claimId
-    ""
+    let sleepestGuardId, sleepestTime = File.ReadAllText "Data/day04.input" |> Day04.getSleepestGuard
+    sprintf "part1 = %A, part2 = " (sleepestGuardId * sleepestTime)
 
 let days : Map<int, unit -> string> =
     [
diff --git a/Tests/Day04 tests.fs b/Tests/Day04 tests.fs
index b952e14..149aae0 100644
--- a/Tests/Day04 tests.fs	
+++ b/Tests/Day04 tests.fs	
@@ -33,7 +33,7 @@ type ``Day04 tests`` (output : ITestOutputHelper) =
                 [1518-11-05 00:55] wakes up
             """
 
-        output.WriteLine (Day04.parseInput input)
+        output.WriteLine (Day04.getSleepestGuard input |> string)
 
         1 =! 2
         ()
-- 
2.45.2