days 1-3

src/bin/02.rs

@@ -0,0 +1,114 @@
+advent_of_code::solution!(2);
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let valid_reports = input.split('\n').fold(0, |total, line| {
+        if line.is_empty() { return total };
+
+        let values: Vec<_> = line.split(" ").map(|f| f.parse::<u32>().unwrap()).collect();
+        let is_valid = is_valid_report(&values);
+        // println!("Report {} {} valid", line, if is_valid { "is" } else { "is NOT" });
+        if is_valid { return total + 1 } else { return total };
+    });
+
+    return Some(valid_reports);
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let valid_reports = input.split('\n').fold(0, |total, line| {
+        if line.is_empty() { return total };
+
+        let values: Vec<_> = line.split(" ").map(|f| f.parse::<u32>().unwrap()).collect();
+
+        let is_valid = is_any_valid_report(&values);
+        // println!("Report {} {} valid", line, if is_valid { "is" } else { "is NOT" });
+        if is_valid { return total + 1 } else { return total };
+    });
+
+    return Some(valid_reports);
+}
+
+enum Direction {
+    Unknown,
+    Increasing,
+    Decreasing,
+}
+
+fn is_valid_report(values: &Vec<u32>) -> bool {
+    let mut direction = Direction::Unknown;
+    // println!("Checking values {:?}", values);
+    let mut last_report = *values.first().unwrap();
+
+    for r in &values[1..] {
+        let report = *r;
+
+        if matches!(direction, Direction::Unknown) {
+            direction = if report > last_report {
+                Direction::Increasing
+            } else {
+                Direction::Decreasing
+            };
+        }
+
+        if report == last_report {
+            return false;
+        };
+        if matches!(direction, Direction::Increasing)
+            && (report < last_report || report > last_report + 3)
+        {
+            return false;
+        };
+        if matches!(direction, Direction::Decreasing)
+            && (report > last_report || report + 3 < last_report)
+        {
+            return false;
+        };
+
+        last_report = report;
+    }
+
+    return true;
+}
+
+fn is_any_valid_report(values: &Vec<u32>) -> bool {
+    if is_valid_report(values) {
+        return true;
+    }
+    let length = values.len();
+    for idx in 0..length {
+        if is_valid_report(&copy_except(values, idx)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+fn copy_except(values: &Vec<u32>, exclude_idx: usize) -> Vec<u32> {
+    let mut new_values: Vec<u32> = Vec::new();
+    let mut idx = 0;
+    for value in values {
+        if idx != exclude_idx {
+            new_values.push(*value);
+        }
+        idx += 1;
+    }
+    // println!("copied new values {:?}", new_values);
+    return new_values;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(2));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(4));
+    }
+}