From e1aa065f7ff41193f2212a8aee9577eb0bfb5a3b Mon Sep 17 00:00:00 2001
From: Aaro Koivukangas <aaro.koivukangas@gmail.com>
Date: Mon, 20 Jan 2025 12:21:00 +0200
Subject: [PATCH] 2024 day2?

---
 2024/day2/Cargo.lock  |   7 +++
 2024/day2/Cargo.toml  |   8 +++
 2024/day2/src/main.rs | 111 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+)
 create mode 100644 2024/day2/Cargo.lock
 create mode 100644 2024/day2/Cargo.toml
 create mode 100644 2024/day2/src/main.rs

diff --git a/2024/day2/Cargo.lock b/2024/day2/Cargo.lock
new file mode 100644
index 0000000..63c2f60
--- /dev/null
+++ b/2024/day2/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day2"
+version = "0.1.0"
diff --git a/2024/day2/Cargo.toml b/2024/day2/Cargo.toml
new file mode 100644
index 0000000..8aa34bb
--- /dev/null
+++ b/2024/day2/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "day2"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/2024/day2/src/main.rs b/2024/day2/src/main.rs
new file mode 100644
index 0000000..1555673
--- /dev/null
+++ b/2024/day2/src/main.rs
@@ -0,0 +1,111 @@
+use std::fs;
+
+fn main() {
+    println!("Hello, world!");
+    let contents = parse_input_file("./input.txt");
+
+    let result1 = solve_part1(&contents);
+    println!("Result part1: {}", result1);
+
+    let result2 = solve_part2(&contents);
+    println!("Result part2: {}", result2);
+}
+
+fn count_results(reports: &Vec<Vec<i32>>, selector: &dyn Fn(&Vec<i32>, i32) -> bool) -> i32 {
+    let mut result: i32 = 0;
+
+    for report in reports {
+        result += match selector(&report, 0) {
+            true => 1,
+            false => 0,
+        }
+    }
+
+    result
+}
+
+fn solve_part1(reports: &Vec<Vec<i32>>) -> i32 {
+    count_results(&reports, &is_monotonic_and_properly_gapped)
+}
+
+fn solve_part2(reports: &Vec<Vec<i32>>) -> i32 {
+    count_results(&reports, &is_monotonic_and_properly_gapped_with_errors)
+}
+
+fn is_monotonic_and_properly_gapped(line: &Vec<i32>, _depth: i32) -> bool {
+    let is_previous_increasing: bool = (line[0] - line[1]) > 0;
+    for idx in 0..(line.len() - 1) {
+        let difference: i32 = line[idx] - line[idx + 1];
+
+        if difference.abs() > 3 || 1 > difference.abs() {
+            return false;
+        }
+
+        if difference > 0 && is_previous_increasing != true {
+            return false;
+        }
+        if difference < 0 && is_previous_increasing == true {
+            return false;
+        }
+    }
+    true
+}
+
+fn is_monotonic_and_properly_gapped_with_errors(line: &Vec<i32>, depth: i32) -> bool {
+    if line.len() < 2 {
+        return false;
+    }
+
+    let is_previous_increasing: bool = (line[0] - line[1]) > 0;
+    for idx in 0..(line.len() - 1) {
+        let difference: i32 = line[idx] - line[idx + 1];
+
+        if difference.abs() > 3 || 1 > difference.abs() {
+            for idx_i in 0..(line.len() - 1) {
+                let mut without_index: Vec<i32> = line.to_owned();
+                without_index.remove(idx_i);
+                if depth >= 0 && is_monotonic_and_properly_gapped_with_errors(&without_index, depth - 1) {
+                    return true;
+                };
+            }
+            return false;
+        }
+
+        if difference > 0 && is_previous_increasing != true {
+            for idx_i in 0..(line.len() - 1) {
+                let mut without_index: Vec<i32> = line.to_owned();
+                without_index.remove(idx_i);
+                if depth >= 0 && is_monotonic_and_properly_gapped_with_errors(&without_index, depth - 1) {
+                    return true;
+                };
+            }
+            return false;
+        }
+        if difference < 0 && is_previous_increasing == true {
+            for idx_i in 0..(line.len() - 1) {
+                let mut without_index: Vec<i32> = line.to_owned();
+                without_index.remove(idx_i);
+                if depth >= 0 && is_monotonic_and_properly_gapped_with_errors(&without_index, depth - 1) {
+                    return true;
+                };
+            }
+            return false;
+        }
+    }
+    true
+}
+
+fn parse_input_file(filename: &str) -> Vec<Vec<i32>> {
+    let mut reports: Vec<Vec<i32>> = Vec::new();
+    let file = fs::read_to_string(filename).expect("Should open the file");
+
+    for line in file.lines() {
+        let numbers: Vec<i32> = line
+            .split_whitespace()
+            .map(|num| num.parse::<i32>().unwrap())
+            .collect::<Vec<i32>>();
+        reports.push(numbers);
+    }
+
+    reports
+}