feat: part 1 of day 4

ankjevel · ankjevel · commit 8bec8362a997 · 2020-12-05T12:05:08.000+01:00
diff --git a/day04/Cargo.toml b/day04/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "day04"
+version = "0.1.0"
+authors = ["Dennis Pettersson <mail@dennispettersson.se>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/day04/src/main.rs b/day04/src/main.rs
@@ -0,0 +1,30 @@
+#![feature(label_break_value)]
+
+use std::io::Result;
+
+mod part_01;
+
+use part_01::main as part_01;
+
+const PUZZLE_INPUT: &'static str = "347312-805915";
+
+fn main() -> Result<()> {
+    'part_01: {
+        println!("part_01: {}", part_01(&PUZZLE_INPUT).unwrap());
+    }
+
+    'part_02: {}
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_gets_the_right_answer_for_examples() {
+        assert_eq!(true, part_01::meet_criteria("111111"));
+        assert_eq!(false, part_01::meet_criteria("223450"));
+        assert_eq!(false, part_01::meet_criteria("123789"));
+    }
+}
diff --git a/day04/src/part_01.rs b/day04/src/part_01.rs
@@ -0,0 +1,41 @@
+use std::io::Result;
+
+pub fn meet_criteria(input: &str) -> bool {
+    let bytes: Vec<_> = input
+        .chars()
+        .map(|c| c.to_string().parse::<u8>().unwrap())
+        .collect();
+
+    let mut pairs = false;
+    let mut never_decrese = true;
+    for i in 1..bytes.len() {
+        let current = bytes[i];
+        let prev = bytes[i - 1];
+        if never_decrese == false {
+            break;
+        }
+
+        pairs = pairs || current == prev;
+
+        never_decrese = current >= prev;
+    }
+
+    pairs && never_decrese
+}
+
+pub fn main(input: &str) -> Result<u32> {
+    let range = &input
+        .split('-')
+        .map(|part| part.parse::<u32>().unwrap())
+        .collect::<Vec<u32>>();
+
+    let mut count = 0;
+    for i in range[0]..range[1] {
+        let string = i.to_string();
+        if meet_criteria(&string) {
+            count += 1;
+        }
+    }
+
+    Ok(count)
+}
