cleaned up and commented (ChatGPT) version of day2

Author: simonschnake

Diff for: julia/day2.jl

@@ -0,0 +1,48 @@
+# Read the input file containing the reports, each report is a line of space-separated numbers.
+input = readlines("inputs/day2")
+
+# Parse the input into an array of arrays, where each sub-array represents a report of integers.
+reports = map(input) do x
+    x = split(x, " ")            # Split each line into individual strings (numbers).
+    x = parse.(Int, x)           # Convert the strings to integers.
+end
+
+# Function to check if a report is "safe".
+# A report is safe if the levels are all increasing or all decreasing
+# and the difference between any two adjacent levels is between 1 and 3 inclusive.
+function report_is_save(report)
+    delta = report[2:end] - report[1:end-1]  # Calculate differences between adjacent levels.
+    
+    # Check if all differences are either positive (increasing) or negative (decreasing).
+    if !(all(delta .> 0) || all(delta .< 0))
+        return false                         # If not, the report is unsafe.
+    end
+
+    delta = abs.(delta)                      # Take the absolute value of the differences.
+
+    # Check if the maximum difference is greater than 3.
+    if maximum(delta) > 3
+        return false                         # If so, the report is unsafe.
+    end
+
+    return true                              # If both conditions are met, the report is safe.
+end
+
+# Calculate and print the result for Part 1: Count the number of safe reports.
+println("Result Part 1: ", report_is_save.(reports) |> sum)  
+
+# Function to check if a report can be made safe by tolerating a single "bad" level.
+function is_save_tolerate_a_single(report)
+    # Iterate through each level in the report.
+    for i in eachindex(report)
+        xd = deleteat!(copy(report), i)      # Remove the i-th level from the report.
+        if report_is_save(xd)                # Check if the modified report is safe.
+            return true                      # If so, return true.
+        end
+    end
+    return false                             # If no single level can be removed to make it safe, return false.
+end
+
+# Calculate and print the result for Part 2: Count the number of reports that are either
+# inherently safe or can be made safe by tolerating a single bad level.
+println("Result Part 2: ", is_save_tolerate_a_single.(reports) |> sum)