Advent 2023 Day 7, 8 & 9

advent_of_code_2023/day9/main1.rs

@@ -0,0 +1,26 @@
+use std::fs::read_to_string;
+
+fn extrapolate(sequence: &Vec<i64>) -> i64 {
+    if sequence.iter().all(|num| { *num == 0 }) {
+        return 0;
+    }
+
+    let mut deltas: Vec<i64> = Vec::new();
+    for idx in 1..sequence.len() {
+        deltas.push(sequence[idx] - sequence[idx - 1]);
+    }
+
+    sequence.last().unwrap() + extrapolate(&deltas)
+}
+
+fn main() {
+    let sequences = read_to_string("input.txt").unwrap().lines().map(|line| {
+        line.split(' ').map(|num| {
+            num.parse::<i64>().unwrap()
+        }).collect::<Vec<_>>()
+    }).collect::<Vec<_>>();
+
+    println!("Sum of extrapolations: {}", sequences.iter().map(|sequence| {
+        extrapolate(sequence)
+    }).sum::<i64>());
+}