01 organized and 02 base logic done

src/advent_of_code/mod.rs

@@ -1,3 +1,4 @@
+mod mon_02;
 mod sun_01;
 mod types;
 mod utils;
@@ -9,8 +10,13 @@ pub fn today() {
 }
 
 pub fn historian_hysteria() {
-    let key = sun_01::sun_01("./assets/day_1_input").unwrap();
+    // Sunday 01
+    let key = sun_01::get_key("./assets/day_1_input").unwrap();
     println!("The key is: {key}");
     let similarity = sun_01::get_similarity("./assets/day_1_input");
     println!("The similarity is: {similarity}");
+
+    // Monday 02
+    let safe_report_count = mon_02::check_reports_safety("");
+    println!("There are {safe_report_count} safe reports");
 }

src/advent_of_code/mon_02.rs

@@ -1,3 +1,59 @@
+use utils::calc_distance;
+
 use super::*;
 
-pub fn mon_02() {}
+pub fn check_reports_safety(input: &str) -> ReportSafety {
+    let report_list: [[Report; 5]; 6] = [
+        [7, 6, 4, 2, 1],
+        [1, 2, 7, 8, 9],
+        [9, 7, 6, 2, 1],
+        [1, 3, 2, 4, 5],
+        [8, 6, 4, 4, 1],
+        [1, 3, 6, 7, 9],
+    ];
+
+    let mut safe_count: ReportSafety = 0;
+
+    // 1. All levels must be all increasing or decreasing
+    // 2. All levels must change by at leat one and at most three
+
+    for report in report_list {
+        if report.len() < 2 {
+            safe_count += 1;
+            break;
+        }
+
+        let mut safe = true;
+        let initial_direction: ReportDirection = get_report_direction(&report[0..=1]);
+
+        'report_check: for index in 1..report.len() {
+            let prev = index - 1;
+            let distance = calc_distance(report[index], report[prev]);
+            let direction = get_report_direction(&[report[prev], report[index]]);
+
+            if report[index] == report[prev]
+                || distance < 1
+                || distance > 3
+                || direction != initial_direction
+            {
+                safe = false;
+                break 'report_check;
+            }
+        }
+
+        if safe {
+            safe_count += 1;
+        }
+    }
+
+    safe_count
+}
+
+// FIXME: this is not a good function, since may try to access an invalid index
+fn get_report_direction(report: &[Report]) -> ReportDirection {
+    if report[1] - report[0] > 0 {
+        ReportDirection::Increasing
+    } else {
+        ReportDirection::Decreasing
+    }
+}

src/advent_of_code/sun_01.rs

@@ -1,8 +1,6 @@
-use std::ops::Sub;
-
 use super::*;
 
-pub fn sun_01(input: &str) -> Result<Key, ()> {
+pub fn get_key(input: &str) -> Result<Key, ()> {
     let mut key: Id = 0;
 
     let (mut list_1, mut list_2) = utils::read_id_lists(input);
@@ -17,7 +15,7 @@ pub fn sun_01(input: &str) -> Result<Key, ()> {
 
     // 2. Calc the distance between the pair elements
     for index in 0..list_1.len() {
-        key += calc_distance(list_1[index], list_2[index]);
+        key += utils::calc_distance(list_1[index], list_2[index]);
     }
 
     Ok(key)
@@ -41,13 +39,3 @@ pub fn get_similarity(input: &str) -> Similarity {
 
     similarity
 }
-
-fn calc_distance<T>(num_1: T, num_2: T) -> T
-where
-    T: PartialOrd + Sub<Output = T>,
-{
-    if num_1 > num_2 {
-        return num_1 - num_2;
-    }
-    return num_2 - num_1;
-}

src/advent_of_code/types.rs

@@ -1,3 +1,12 @@
 pub type Id = i32;
 pub type Key = Id;
 pub type Similarity = Id;
+
+pub type Report = i32;
+pub type ReportSafety = u32;
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum ReportDirection {
+    Increasing,
+    Decreasing,
+}

src/advent_of_code/utils.rs

@@ -1,4 +1,5 @@
 use std::fs::read_to_string;
+use std::ops::Sub;
 
 use super::*;
 
@@ -15,3 +16,15 @@ pub fn read_id_lists(input: &str) -> (Vec<Id>, Vec<Id>) {
 
     return (list_1, list_2);
 }
+
+pub fn read_report_list(input: &str) {}
+
+pub fn calc_distance<T>(num_1: T, num_2: T) -> T
+where
+    T: PartialOrd + Sub<Output = T>,
+{
+    if num_1 > num_2 {
+        return num_1 - num_2;
+    }
+    return num_2 - num_1;
+}