split direction (asc/desc) from state (Good/Bad/Dampening)

day_02/src/main.rs

@@ -21,79 +21,114 @@ where
 }
 
 #[derive(Eq, PartialEq)]
-enum LevelTransitionState {
-    Asc,
-    Desc,
-    Bad,
-    Dampened,
+enum TransitionState {
+    Good,     // Good state
+    Bad,      // Bad state
+    Dampened, // Could be removed to make a good state
 }
 
-fn compare_levels(curr_level: i64, next_level: i64) -> LevelTransitionState {
+#[derive(Eq, PartialEq)]
+enum TransitionDirection {
+    Asc,  // level is increasing
+    Desc, // level is decreasing
+}
+
+struct LevelTransition {
+    state: TransitionState,
+    direction: TransitionDirection,
+}
+/// Given two level inputs, return one of the following:
+///   - `LevelTransitionState::Bad` if the difference between
+///     the levels is either 0 or great than 3
+///   - `LevelTransitionState::Asc` if the value from curr_level to next_level is increasing and it's not BAD
+///   - `LevelTransitionState::Desc` if the value from curr_level to next_level is decreasing and it's not BAD
+fn compare_levels(curr_level: i64, next_level: i64) -> LevelTransition {
     let level_diff = next_level - curr_level;
 
-    // If the diff is 0 or greater than 3, return bad stat
-    if level_diff == 0 || level_diff.abs() > 3 {
-        return LevelTransitionState::Bad;
-    }
+    // If the diff is 0 or greater than 3, return bad state
+    let state = if level_diff == 0 || level_diff.abs() > 3 {
+        TransitionState::Bad
+    } else {
+        TransitionState::Good
+    };
+
     // If great than zero they are ascending
-    if level_diff > 0 {
-        return LevelTransitionState::Asc;
-    }
-    //Else we're descending
-    return LevelTransitionState::Desc;
+    let direction = if level_diff > 0 {
+        TransitionDirection::Asc
+    } else {
+        TransitionDirection::Desc
+    };
+
+    return LevelTransition { state, direction };
 }
 
-fn is_report_safe(report: Vec<i64>) -> bool {
+fn is_report_safe_no_dampening(report: Vec<i64>) -> bool {
     // Turn the report into a bunch of states for each adjacent pair in the report
-    let report: Vec<LevelTransitionState> = report
+    let report: Vec<LevelTransition> = report
         .windows(2)
         .map(|l| compare_levels(l[0], l[1]))
         .collect();
 
     // Setup the loop by checking the first start as a special case
-    let mut prev_state = &report[0];
-    if prev_state == &LevelTransitionState::Bad {
+    let mut prev_transition = &report[0];
+    if prev_transition.state != TransitionState::Good {
         return false;
     }
 
     // Check each state
-    for level_state in report[1..].iter() {
+    for level_transition in report[1..].iter() {
         // If bad, then it's just bad
-        if level_state == &LevelTransitionState::Bad {
+        if level_transition.state != TransitionState::Good {
             return false;
         }
 
         // If the states aren't the same as the prev, it must
         // have changed direction
-        if level_state != prev_state {
+        if level_transition.direction != prev_transition.direction {
             return false;
         }
 
         // Setup for next iteration
-        prev_state = level_state;
+        prev_transition = level_transition;
     }
     return true;
 }
 
+// fn is_report_safe_with_dampening(report: Vec<i64>) -> bool {
 //     let mut modified_report: Vec<Option<i64>> = vec![None];
 //     let mut tmp_report: Vec<Option<i64>> = report.iter().map(|v| Some(*v)).collect();
 //     modified_report.append(&mut tmp_report);
 //     modified_report.push(None);
-// dbg!(modified_report);
 
 //     let states = Vec::new();
 //     for window in modified_report.windows(3) {
 //         let window_tuple = (window[0], window[1], window[2]);
 //         let state = match window_tuple {
-//         (None, Some(curr), Some(next)) => {
-//             let diff = curr
+//             (None, Some(curr), Some(next)) | (Some(curr), Some(next), None)  => {
+//                 // Matched first or last element, which means we only have one check to do
+//                 // and we always return Dampened instead of Bad
+//                 let local_state = compare_levels(curr, next);
+//                 if local_state == TransitionState::Bad {
+//                     // shadow bad with dampened since can always
+//                     // remove the first and last element.
+//                     TransitionState::Dampened
+//                 } else {
+//                     local_state
+//                 }
+//             },
+//             (Some(prev), Some(curr), Some(next)) => {
+//                 let first_state = compare_levels(prev, curr);
+//                 let second_state = compare_levels(curr, next);
+//                 if first_state == TransitionState::Bad || second_state == TransitionState::Bad || first_state != second_state {
+
+//                 }
 //             },
-//         (Some(prev), Some(curr), Some(next)) => (),
-//         (Some(prev), Some(curr), None) => (),
 //             _ => panic!("This should never happen!"),
 //         }
 //         states.push(state);
 //     }
+//     true
+// }
 
 fn main() -> Result<(), Box<dyn Error>> {
     // Handle command input
@@ -109,16 +144,19 @@ fn main() -> Result<(), Box<dyn Error>> {
     let input_file = File::open(input_file_string)?;
     let input_reader = BufReader::new(input_file);
 
-    let mut accumulator = 0;
+    let mut accumulator_no_dampening = 0;
     for line in input_reader.lines() {
         let line = line?;
         let parsed_report: Vec<i64> = parse_report(&line)?;
-        if is_report_safe(parsed_report) {
-            accumulator += 1;
+        if is_report_safe_no_dampening(parsed_report) {
+            accumulator_no_dampening += 1;
         }
     }
 
-    println!("Number of SAFE reports: {}", accumulator);
+    println!(
+        "Number of SAFE reports (No Dampening - Part 1): {}",
+        accumulator_no_dampening
+    );
 
     Ok(())
 }