From 5cf79c7fe2c14fc830f567d61abbe4c75b5f9b8c Mon Sep 17 00:00:00 2001
From: Baipyrus <simon.waltemathe@gmail.com>
Date: Wed, 24 Jan 2024 18:38:59 +0100
Subject: [PATCH] differentiate sequence and extrapolate

---
 src/day09/mod.rs | 45 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/src/day09/mod.rs b/src/day09/mod.rs
index ef4c54c..69e51e2 100644
--- a/src/day09/mod.rs
+++ b/src/day09/mod.rs
@@ -7,11 +7,44 @@ pub fn main() {
     let content = read_file(name);
     let lines = split_lines(&content);
     let input = split_inputs(lines, &r"\s+");
+
     let sequences = convert_num(input);   
-    
-    let sum_input_0: i32 = sequences[0]
-        .clone()
-        .into_iter()
-        .sum();
-    println!("Erste Summe: {sum_input_0}");
+    let structures: Vec<Vec<Vec<i32>>> = sequences
+        .iter()
+        .map(|s| extrapolate(s.to_vec()))
+        .collect();
+
+    for seq in structures[0].clone() {
+        for n in seq {
+            print!("{n} ");
+        }
+        println!("");
+    }
+}
+
+fn extrapolate(seq: Vec<i32>) -> Vec<Vec<i32>> {
+    let mut structure = vec![seq]; 
+    let mut index = 0;
+
+    loop {
+        let current = &structure[index];
+        let diff = seq_diff(current.to_vec());
+        
+        if diff.iter().all(|&n| n == 0) {
+            break structure;
+        }
+
+        structure.push(diff);
+        index += 1;
+    }
+}
+
+fn seq_diff(seq: Vec<i32>) -> Vec<i32> {
+    let mut diff = Vec::new();
+
+    for (i, n) in seq.iter().skip(1).enumerate() {
+        diff.push(n - seq[i]);
+    }
+
+    diff
 }