2022/02 comments

encse · encse · commit 48fc3bd0f36e · 2022-12-31T21:11:02.000+01:00
diff --git a/2022/Day02/Solution.cs b/2022/Day02/Solution.cs
@@ -6,11 +6,15 @@ namespace AdventOfCode.Y2022.Day02;
 [ProblemName("Rock Paper Scissors")]
 class Solution : Solver {
 
-    // There are many obscure ways of solving this challenge, this is a 
-    // rather explicit one. We parse the input lines into a pair of
-    // Rock/Paper/Scissors signs represented as 1,2,3 (the values from the
-    // problem description). We calculate the score for each pair and sum up
-    // the result.
+    // There are many obscure ways of solving this challenge. You can use 
+    // mod 3 arithmetic or play with ASCII encoding. This approach is a more 
+    // explicit one. I think it is as simple as it gets.
+
+    // We parse the input lines into a pair of Rock/Paper/Scissors signs 
+    // represented by 1,2,3 (the values from the problem description), 
+    // calculate the score for each pair and sum it up.
+
+    // Part one and two differs only in the decoding of the X, Y and Z signs.
 
     enum Sign {
         Rock = 1,
@@ -19,44 +23,44 @@ enum Sign {
     }
 
     public object PartOne(string input) => (
-            from match in input.Split('\n')
-                let elf = 
-                    match[0] == 'A' ? Sign.Rock :
-                    match[0] == 'B' ? Sign.Paper :
-                    match[0] == 'C' ? Sign.Scissors :
-                         throw new ArgumentException(match)
-                let you = 
-                    match[2] == 'X' ? Sign.Rock :
-                    match[2] == 'Y' ? Sign.Paper :
-                    match[2] == 'Z' ? Sign.Scissors :
-                                      throw new ArgumentException(match)
-            select Score(elf, you)
-        ).Sum();
+        from line in input.Split('\n')
+            let elf = 
+                line[0] == 'A' ? Sign.Rock :
+                line[0] == 'B' ? Sign.Paper :
+                line[0] == 'C' ? Sign.Scissors :
+                                 throw new ArgumentException(line)
+            let you = 
+                line[2] == 'X' ? Sign.Rock :
+                line[2] == 'Y' ? Sign.Paper :
+                line[2] == 'Z' ? Sign.Scissors :
+                                 throw new ArgumentException(line)
+        select Score(elf, you)
+    ).Sum();
 
     public object PartTwo(string input) => (
-            from match in input.Split('\n')
-                let elf = 
-                    match[0] == 'A' ? Sign.Rock :
-                    match[0] == 'B' ? Sign.Paper :
-                    match[0] == 'C' ? Sign.Scissors :
-                                      throw new ArgumentException(match)
-                let you = 
-                    match[2] == 'X' ? Next(Next(elf)): // elf wins
-                    match[2] == 'Y' ? elf :            // draw
-                    match[2] == 'Z' ? Next(elf) :      // you win
-                                      throw new ArgumentException(match)
-            select Score(elf, you)
-        ).Sum();
+        from line in input.Split('\n')
+            let elf = 
+                line[0] == 'A' ? Sign.Rock :
+                line[0] == 'B' ? Sign.Paper :
+                line[0] == 'C' ? Sign.Scissors :
+                                 throw new ArgumentException(line)
+            let you = 
+                line[2] == 'X' ? Next(Next(elf)): // elf wins
+                line[2] == 'Y' ? elf :            // draw
+                line[2] == 'Z' ? Next(elf) :      // you win
+                                 throw new ArgumentException(line)
+        select Score(elf, you)
+    ).Sum();
     
     int Score(Sign elfSign, Sign yourSign) =>
         yourSign == Next(elfSign)       ? 6 + (int)yourSign : // you win
         yourSign == elfSign             ? 3 + (int)yourSign : // draw
         yourSign == Next(Next(elfSign)) ? 0 + (int)yourSign : // elf wins
-        throw new ArgumentException();
+                                          throw new ArgumentException();
 
     Sign Next(Sign sign) => 
         sign == Sign.Rock     ? Sign.Paper : 
         sign == Sign.Paper    ? Sign.Scissors : 
         sign == Sign.Scissors ? Sign.Rock : 
-        throw new ArgumentException();
+                                throw new ArgumentException();
 }
