update day9

src/day9.rs

@@ -0,0 +1,85 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+#[aoc_generator(day9)]
+fn parse(input: &str) -> Vec<Vec<i64>> {
+    let input: Vec<_> = input.split('\n')
+        .map(|line| {
+            line.split_whitespace()
+                .map(|num| num.parse::<i64>().unwrap())
+                .collect::<Vec<_>>()
+        }).collect();
+
+        input
+}
+
+#[aoc(day9, part1)]
+fn part1(input: &Vec<Vec<i64>>) -> i64 {
+    let mut total = 0;
+
+    for line in input {
+        let mut line_enders: Vec<i64> = vec![*line.last().unwrap()];
+        let mut cur_line: Vec<i64> = line.to_vec();
+        while !cur_line.iter().all(|x| *x == 0) {
+            let mut next_line: Vec<i64> = vec![];
+            for i in 1..cur_line.len() {
+                let diff = cur_line[i] - cur_line[i-1];
+                next_line.push(diff)
+            }
+            line_enders.push(*next_line.last().unwrap());
+            cur_line = next_line;
+        }
+
+        let mut sum = 0;
+        for i in (1..line_enders.len()).rev() {
+            sum = sum + line_enders[i - 1];
+        }
+        total += sum;
+    }
+
+    total
+}
+
+#[aoc(day9, part2)]
+fn part2(input: &Vec<Vec<i64>>) -> i64 {
+    let mut total = 0;
+
+    for line in input {
+        let mut line_starters: Vec<i64> = vec![*line.first().unwrap()];
+        let mut cur_line: Vec<i64> = line.to_vec();
+        while !cur_line.iter().all(|x| *x == 0) {
+            let mut next_line: Vec<i64> = vec![];
+            for i in 1..cur_line.len() {
+                let diff = cur_line[i] - cur_line[i-1];
+                next_line.push(diff)
+            }
+            line_starters.push(*next_line.first().unwrap());
+            cur_line = next_line;
+        }
+
+        let mut sum = 0;
+        for i in (1..line_starters.len()).rev() {
+            sum = line_starters[i - 1] - sum;
+        }
+        total += sum;
+    }
+    total
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const EX: &str = r"0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EX)), 114);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EX)), 2);
+    }
+}

src/lib.rs

@@ -1,3 +1,4 @@
+mod day9;
 mod day8;
 mod day7;
 mod day6;