finish day 1

src/day_1.rs

@@ -0,0 +1,23 @@
+use std::fs;
+
+pub fn day_1() -> String {
+    let input = fs::read_to_string("input/day_1.txt").unwrap();
+
+    let elves: Vec<&str> = input.split("\n\n").collect();
+
+    let mut highest_calorie_count: u64 = 0;
+
+    for meals in elves.iter() {
+        let mut elf_calorie_count= 0;
+
+        for meal in meals.split_whitespace() {
+            elf_calorie_count += meal.parse().unwrap_or(0);
+        }
+
+        if elf_calorie_count > highest_calorie_count {
+            highest_calorie_count = elf_calorie_count;
+        }
+    }
+
+    format!("{highest_calorie_count}")
+}