day4

day4/src/main.rs

@@ -0,0 +1,7 @@
+mod part1;
+mod part2;
+
+fn main() {
+    println!("# Part 1: {}", part1::get_total_points());
+    println!("# Part 2: {}", part2::get_total_cards());
+}

day4/src/part1.rs

@@ -0,0 +1,41 @@
+pub fn get_total_points() -> u32 {
+    let data1 = util::get_data("data1.txt");
+
+    let mut sum: u32 = 0;
+
+    for i in 0..data1.len() {
+        let split: Vec<&str> = data1[i].split(":").collect();
+        let numbers: Vec<&str> = split[1].split("|").collect();
+
+        let winning = get_numbers_from_str(numbers[0]);
+        let card = get_numbers_from_str(numbers[1]);
+
+        sum += get_game_points(&winning, &card);
+    }
+
+    return sum;
+}
+
+fn get_game_points(w: &Vec<usize>, c: &Vec<usize>) -> u32 {
+    let shared_len = c
+        .iter()
+        .filter(|x| w.contains(x))
+        .collect::<Vec<&usize>>()
+        .len();
+
+    if shared_len == 0 {
+        return 0;
+    }
+
+    let base: u32 = 2;
+
+    return base.pow((shared_len - 1) as u32);
+}
+
+fn get_numbers_from_str(str: &str) -> Vec<usize> {
+    return str
+        .split(" ")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.trim().parse().expect("failed to parse"))
+        .collect();
+}

day4/src/part2.rs

@@ -0,0 +1,54 @@
+use std::collections::HashMap;
+
+pub fn get_total_cards() -> usize {
+    let data = util::get_data("data2.txt");
+
+    let mut m: HashMap<usize, usize> = HashMap::new();
+
+    for i in 0..data.len() {
+        m.entry(i).and_modify(|v| *v += 1).or_insert(1);
+
+        let count = get_count(&m, i);
+
+        let split: Vec<&str> = data[i].split(":").collect();
+        let numbers: Vec<&str> = split[1].split("|").collect();
+
+        let winning = get_numbers_from_str(numbers[0]);
+        let card = get_numbers_from_str(numbers[1]);
+
+        let shared_len = card
+            .iter()
+            .filter(|x| winning.contains(x))
+            .collect::<Vec<&usize>>()
+            .len();
+
+        for j in 0..shared_len {
+            let k = i + j + 1;
+            if k < data.len() {
+                m.entry(k).and_modify(|v| *v += count).or_insert(count);
+            }
+        }
+    }
+
+    return m.iter().map(|(_, v)| v).sum();
+}
+
+fn get_count(m: &HashMap<usize, usize>, i: usize) -> usize {
+    let count = match m.get(&i) {
+        Some(n) => n,
+        None => {
+            println!("should always have a value, {:?}, {:?}", m, i);
+            return 0;
+        }
+    };
+
+    return *count;
+}
+
+fn get_numbers_from_str(str: &str) -> Vec<usize> {
+    return str
+        .split(" ")
+        .filter(|x| !x.is_empty())
+        .map(|x| x.trim().parse().expect("failed to parse"))
+        .collect();
+}