Implement 2025 - Day 2 - Part 1

2025/02.rs

@@ -0,0 +1,36 @@
+---cargo
+---
+
+static CONTENT: &'static str = include_str!("./inputs/02_1.txt");
+
+fn main() {
+    let ranges: Vec<_> = CONTENT.split(',').map(|l| l.trim()).filter(|l| !l.is_empty()).map(|l| {
+        let (raw_start, raw_end) = l.split_once('-').unwrap();
+        let start: usize = raw_start.parse().unwrap();
+        let end: usize = raw_end.parse().unwrap();
+
+        start..=end
+    }).collect();
+
+    println!("Ranges: {:?}", ranges);
+
+    let mut result = 0;
+    for r in ranges.iter() {
+        for v in r.clone() {
+            let len = v.ilog10() + 1;
+            if len % 2 != 0 {
+                continue;
+            }
+
+            let first_half = v / 10_usize.pow(len/2);
+            let second_half = v - (first_half * 10_usize.pow(len/2));
+
+            if first_half == second_half {
+                result += v;
+                println!("Invalid {} - Halves ({}, {})", v, first_half, second_half);
+            }
+        }
+    }
+
+    println!("Result: {}", result);
+}