2025 - Day 2 part 1 - rust

2025/rust2/src/main.rs

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+use std::fs::File;
+use std::io::{BufRead, BufReader};
+
+fn main() {
+    // let filename = "../2/input_example.txt";
+    let filename = "../2/input.txt";
+    let file = BufReader::new(File::open(filename).expect("Unable to open file"));
+
+    // let mut ranges: Vec<String> = Vec::new();
+    let mut ranges: Vec<Vec<u8>> = Vec::new();
+    let mut bad_id: Vec<u64> = Vec::new();
+
+    for line in file.lines() {
+        let wline: String = line.unwrap();
+        let sranges: Vec<&str> = wline.split(',').collect();
+
+        for s in sranges {
+            let range: Vec<u64> = s.split('-').map(|x| x.parse().unwrap()).collect();
+            // println!("{:?}", range);
+            for id in range[0]..range[1] + 1 {
+                let s = id.to_string().into_bytes();
+                ranges.push(s);
+            }
+        }
+    }
+    println!("number of ranges to inspect {:?}", ranges.len());
+    // println!("{:?}", ranges);
+
+    for product_id in ranges {
+        if product_id.len() % 2 == 1 {
+            continue;
+        }
+        let pivot = product_id.len() / 2;
+        let mut bad: bool = true;
+        for i in 0..pivot {
+            if product_id[i] != product_id[pivot + i] {
+                bad = false;
+                break;
+            }
+        }
+        if bad {
+            let num = str::from_utf8(&product_id).unwrap();
+            bad_id.push(num.parse().unwrap())
+        }
+    }
+    // println!("bad ids {:?}", bad_id);
+    let sum: u64 = bad_id.iter().sum();
+
+    println!("{}", sum)
+}