day6 solution 1

1 files changed, 48 insertions, 0 deletions

diff --git a/src/bin/day6.rs b/src/bin/day6.rs
new file mode 100644
index 0000000..3d450cb
--- /dev/null
+++ b/src/bin/day6.rs
@@ -0,0 +1,48 @@
+static DAY: u8 = 6;
+
+fn main() {
+    let input = advent::read_lines(DAY);
+    println!("{DAY}a: {}", possible_ways(&input));
+    println!("{DAY}b: {}", 0);
+}
+
+fn possible_ways(input: &[String]) -> u32 {
+    let get_numbers = |x: &str| {
+        x.split_once(':').unwrap().1.to_string()
+         .split(' ')
+         .filter(|s| !s.is_empty())
+         .map(|s| s.parse().unwrap())
+         .collect::<Vec<u32>>()
+    };
+    let times = get_numbers(&input[0]);
+    let distances = get_numbers(&input[1]);
+
+    let mut ways_list = Vec::new();
+    for (time, record) in times.iter().zip(distances.iter()) {
+        let mut ways = 0;
+        for hold_button in 1 .. *time {
+            let moving_time = time - hold_button;
+            let boat_distance = moving_time * hold_button;
+            if boat_distance > *record {
+                ways += 1;
+            }
+        }
+        ways_list.push(ways);
+    }
+    ways_list.iter()
+             .product()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = [
+            "Time:      7  15   30",
+            "Distance:  9  40  200",
+        ].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
+        assert_eq!(possible_ways(&input), 288);
+    }
+}