add: d03

2025/03/p1.rs

@@ -0,0 +1,34 @@
+use std::cmp::Ordering;
+
+fn cmp_with_eq_as_gt<T: Ord>(a: &T, b: &T) -> Ordering {
+    let order = a.cmp(b);
+    if order == Ordering::Equal {
+        Ordering::Greater
+    } else {
+        order
+    }
+}
+
+#[unsafe(no_mangle)]
+fn challenge_usize(buf: &[u8]) -> usize {
+    let mut total_joltage = 0;
+
+    let s = unsafe { str::from_utf8_unchecked(buf) };
+    for array in s.trim().split('\n') {
+        let bats = array.as_bytes();
+        let bats_but_last = &bats[0..(bats.len() - 1)];
+
+        let first_dig = bats_but_last
+            .iter()
+            .enumerate()
+            .max_by(|a, b| cmp_with_eq_as_gt(a.1, b.1))
+            .unwrap();
+        let last_dig = bats[(first_dig.0 + 1)..].iter().max().unwrap();
+
+        println!("-->> {first_dig:?} {last_dig}");
+        let arr_max_jolts = ((first_dig.1 - b'0') * 10) + (last_dig - b'0');
+        total_joltage += Into::<usize>::into(arr_max_jolts);
+    }
+
+    total_joltage
+}