day10

1 files changed, 44 insertions, 0 deletions

diff --git a/src/bin/day10.rs b/src/bin/day10.rs
new file mode 100644
index 0000000..562408b
--- /dev/null
+++ b/src/bin/day10.rs
@@ -0,0 +1,44 @@
+fn main() {
+    let input = [1,3,2,1,1,3,1,1,1,2];
+    println!("10a: {}", lookandsay_times(&input, 40).len());
+    println!("10b: {}", lookandsay_times(&input, 50).len());
+}
+
+fn lookandsay(input: &[u8]) -> Vec<u8> {
+    let mut say = Vec::new();
+
+    let mut count = 1;
+    let mut prev = input[0];
+    for n in input.iter().skip(1) {
+        if *n != prev {
+            say.push(count);
+            say.push(prev);
+            prev = *n;
+            count = 0;
+        }
+        count += 1;
+    }
+    say.push(count);
+    say.push(prev);
+
+    say
+}
+
+fn lookandsay_times(input: &[u8], times: u32) -> Vec<u8> {
+    let mut data = Vec::from(input);
+    for _ in 0..times {
+        data = lookandsay(&data);
+    }
+    data
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        assert_eq!(lookandsay(&[1,1,1,2,2,1]), [3,1,2,2,1,1]);
+        assert_eq!(lookandsay_times(&[1], 5), [3,1,2,2,1,1]);
+    }
+}