day_01

day_01/Cargo.toml

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+[package]
+name = "day_01"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day_01/src/main.rs

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+use std::fs::File;
+use std::io::{self, BufRead};
+use std::path::Path;
+
+fn main() {
+    // File input must exist in the current path
+    if let Ok(lines) = read_lines("./input") {
+        let mut total_part_1: u64 = 0;
+        let mut total_part_2: u64 = 0;
+
+        // Consumes the iterator, returns an (Optional) String
+        for line in lines {
+            if let Ok(ip) = line {
+                // Part 1
+                let v: Vec<_> = ip.matches(char::is_numeric).collect();
+                println!("{}{}", v[0], v[v.len() - 1]);
+                let number_part_1: u64 = format!("{}{}", v[0], v[v.len() - 1])
+                    .parse::<u64>()
+                    .unwrap();
+                total_part_1 = total_part_1 + number_part_1;
+
+                // Part 2
+                // Match all numbers
+                let numeric: Vec<_> = ip.match_indices(char::is_numeric).collect();
+                let zero_str: Vec<_> = ip.match_indices("zero").collect();
+                let one_str: Vec<_> = ip.match_indices("one").collect();
+                let two_str: Vec<_> = ip.match_indices("two").collect();
+                let three_str: Vec<_> = ip.match_indices("three").collect();
+                let four_str: Vec<_> = ip.match_indices("four").collect();
+                let five_str: Vec<_> = ip.match_indices("five").collect();
+                let six_str: Vec<_> = ip.match_indices("six").collect();
+                let seven_str: Vec<_> = ip.match_indices("seven").collect();
+                let eight_str: Vec<_> = ip.match_indices("eight").collect();
+                let nine_str: Vec<_> = ip.match_indices("nine").collect();
+
+                // Create one vector per line
+                let mut v: Vec<_> = vec![];
+                v.extend_from_slice(&numeric);
+                v.extend_from_slice(&zero_str);
+                v.extend_from_slice(&one_str);
+                v.extend_from_slice(&two_str);
+                v.extend_from_slice(&three_str);
+                v.extend_from_slice(&four_str);
+                v.extend_from_slice(&five_str);
+                v.extend_from_slice(&six_str);
+                v.extend_from_slice(&seven_str);
+                v.extend_from_slice(&eight_str);
+                v.extend_from_slice(&nine_str);
+
+                // Sort vector
+                v.sort_by_key(|k| k.0);
+
+                // Convert written numbers
+                let mut v_first = "";
+                match v.first().unwrap().1 {
+                    "zero" => v_first = "0",
+                    "one" => v_first = "1",
+                    "two" => v_first = "2",
+                    "three" => v_first = "3",
+                    "four" => v_first = "4",
+                    "five" => v_first = "5",
+                    "six" => v_first = "6",
+                    "seven" => v_first = "7",
+                    "eight" => v_first = "8",
+                    "nine" => v_first = "9",
+                    _ => v_first = v.first().unwrap().1,
+                }
+
+                let mut v_last = "";
+                match v.last().unwrap().1 {
+                    "zero" => v_last = "0",
+                    "one" => v_last = "1",
+                    "two" => v_last = "2",
+                    "three" => v_last = "3",
+                    "four" => v_last = "4",
+                    "five" => v_last = "5",
+                    "six" => v_last = "6",
+                    "seven" => v_last = "7",
+                    "eight" => v_last = "8",
+                    "nine" => v_last = "9",
+                    _ => v_last = v.last().unwrap().1,
+                }
+
+                // Create 2-digit number of first and last number per line
+                let number_part_2: u64 = format!("{}{}", v_first, v_last).parse::<u64>().unwrap();
+
+                // Add up all numbers
+                total_part_2 = total_part_2 + number_part_2;
+            }
+        }
+
+        println!("Total of part 1 is {}", total_part_1);
+        println!("Total of part 2 is {}", total_part_2);
+    }
+}
+
+// The output is wrapped in a Result to allow matching on errors
+// Returns an Iterator to the Reader of the lines of the file.
+fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
+where
+    P: AsRef<Path>,
+{
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}