bugfix: syntax

src/day09/mod.rs

@@ -1,28 +1,95 @@
 use crate::common::{convert_num, read_file, split_inputs, split_lines};
 
-pub fn main() {
-    let name = "day09";
-    println!("Executing module '{name}' entrypoint . . . ");
+#[allow(dead_code)]
+pub fn part_two() {
+    predict(false);
+}
 
-    let content = read_file(name);
-    let lines = split_lines(&content);
-    let input = split_inputs(lines, &r"\s+");
+#[allow(dead_code)]
+pub fn part_one() {
+    predict(true);
+}
 
-    let sequences = convert_num(input);   
-    let structures: Vec<Vec<Vec<i32>>> = sequences
+fn predict(forward: bool) {
+    let sequences = setup();
+    let predictions: Vec<i32> = sequences
         .iter()
-        .map(|s| extrapolate(s.to_vec()))
+        .map(|s| {
+            let current = s.to_vec();
+            let mut next = extra_diff(current);
+            expand(&mut next, forward);
+            let history = next
+                .first()
+                .unwrap();
+            
+            if forward {
+                history
+                    .last()
+                    .unwrap()
+                    .clone()
+            } else {
+                history
+                    .first()
+                    .unwrap()
+                    .clone()
+            }
+        })
         .collect();
     
-    for seq in structures[0].clone() {
-        for n in seq {
-            print!("{n} ");
+    let sum: i32 = predictions
+        .iter()
+        .sum();
+
+    println!("The sum of all prediction values is: '{sum}'.");
+}
+
+fn expand(strct: &mut Vec<Vec<i32>>, forward: bool) {
+    let last = strct
+        .last_mut()
+        .unwrap();
+    last.push(*last
+        .last()
+        .unwrap()
+    );
+
+    for i in (0..strct.len() - 1).rev() {
+        let last = strct
+            .get(i + 1)
+            .unwrap()
+            .clone();
+        let current = strct
+            .get_mut(i)
+            .unwrap();
+        
+
+        if forward {
+            current.push(
+                current
+                    .last()
+                    .unwrap()
+                    .clone() +
+                last
+                    .last()
+                    .unwrap()
+                    .clone()
+            );
+        } else {
+            current.insert(
+                0,
+                current
+                    .first()
+                    .unwrap()
+                    .clone() -
+                last
+                    .first()
+                    .unwrap()
+                    .clone()
+            );
         }
-        println!("");
     }
 }
 
-fn extrapolate(seq: Vec<i32>) -> Vec<Vec<i32>> {
+fn extra_diff(seq: Vec<i32>) -> Vec<Vec<i32>> {
     let mut structure = vec![seq]; 
     let mut index = 0;
 
@@ -48,3 +115,13 @@ fn seq_diff(seq: Vec<i32>) -> Vec<i32> {
 
     diff
 }
+
+fn setup() -> Vec<Vec<i32>> {
+    let name = "day09";
+    println!("Executing module '{name}' entrypoint . . . ");
+    
+    let content = read_file(name);
+    let lines = split_lines(&content);
+    let input = split_inputs(lines, &r"\s+");
+    convert_num(input)
+}

src/main.rs

@@ -1,7 +1,15 @@
+use std::time::Instant;
+
 mod common;
 mod day09;
 
 fn main() {
     println!("Executing main entrypoint . . . ");
-    day09::main();
+    let now = Instant::now();
+    
+    // day09::part_one();
+    day09::part_two();
+
+    let elapsed = now.elapsed();
+    println!("Execution in {:?}.", elapsed);
 }