Added day09 part 1

Author: Gentleman1983

build.gradle

@@ -4,7 +4,7 @@ plugins {
 
 // project meta data
 group 'de.havox_design.aoc2023'
-version '0.8.1'
+version '0.8.2'
 
 // Switch to gradle "all" distribution.
 wrapper {

day09/README.md

@@ -0,0 +1,91 @@
+# Day 9: Mirage Maintenance ---
+You ride the camel through the sandstorm and stop where the ghost's maps told you to stop. The sandstorm subsequently 
+subsides, somehow seeing you standing at an **oasis**!
+
+The camel goes to get some water and you stretch your neck. As you look up, you discover what must be yet another giant 
+floating island, this one made of metal! That must be where the **parts to fix the sand machines** come from.
+
+There's even a [hang glider](https://en.wikipedia.org/wiki/Hang_gliding) partially buried in the sand here; once the 
+sun rises and heats up the sand, you might be able to use the glider and the hot air to get all the way up to the metal 
+island!
+
+While you wait for the sun to rise, you admire the oasis hidden here in the middle of Desert Island. It must have a 
+delicate ecosystem; you might as well take some ecological readings while you wait. Maybe you can report any 
+environmental instabilities you find to someone so the oasis can be around for the next sandstorm-worn traveler.
+
+You pull out your handy **Oasis And Sand Instability Sensor** and analyze your surroundings. The OASIS produces a 
+report of many values and how they are changing over time (your puzzle input). Each line in the report contains the 
+**history** of a single value. For example:
+```
+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45
+```
+To best protect the oasis, your environmental report should include a **prediction of the next value** in each history. 
+To do this, start by making a new sequence from the **difference at each step** of your history. If that sequence is 
+**not** all zeroes, repeat this process, using the sequence you just generated as the input sequence. Once all of the 
+values in your latest sequence are zeroes, you can extrapolate what the next value of the original history should be.
+
+In the above dataset, the first history is `0 3 6 9 12 15`. Because the values increase by `3` each step, the first 
+sequence of differences that you generate will be `3 3 3 3 3`. Note that this sequence has one fewer value than the 
+input sequence because at each step it considers two numbers from the input. Since these values aren't **all zero**, 
+repeat the process: the values differ by `0` at each step, so the next sequence is `0 0 0 0`. This means you have 
+enough information to extrapolate the history! Visually, these sequences can be arranged like this:
+```
+0   3   6   9  12  15
+  3   3   3   3   3
+    0   0   0   0
+```
+To extrapolate, start by adding a new zero to the end of your list of zeroes; because the zeroes represent differences 
+between the two values above them, this also means there is now a placeholder in every sequence above it:
+```
+0   3   6   9  12  15  _B_
+  3   3   3   3   3  _A_
+    0   0   0   0  _0_
+```
+You can then start filling in placeholders from the bottom up. `A` needs to be the result of increasing `3` (the value 
+to its left) by `0` (the value below it); this means `A` must be `3`:
+```
+0   3   6   9  12  15   B
+  3   3   3   3  _3_ _3_
+    0   0   0   0  _0_
+```
+Finally, you can fill in `B`, which needs to be the result of increasing `15` (the value to its left) by `3` (the value 
+below it), or **`18`**:
+```
+0   3   6   9  12 _15_ _18_
+  3   3   3   3   3  _3_
+    0   0   0   0   0
+```
+So, the next value of the first history is **`18`**.
+
+Finding all-zero differences for the second history requires an additional sequence:
+```
+1   3   6  10  15  21
+  2   3   4   5   6
+    1   1   1   1
+      0   0   0
+```
+Then, following the same process as before, work out the next value in each sequence from the bottom up:
+```
+1   3   6  10  15  21 _28_
+  2   3   4   5   6  _7_
+    1   1   1   1  _1_
+      0   0   0  _0_
+```
+So, the next value of the second history is **`28`**.
+
+The third history requires even more sequences, but its next value can be found the same way:
+```
+10  13  16  21  30  45 _68_
+   3   3   5   9  15 _23_
+     0   2   4   6  _8_
+       2   2   2  _2_
+         0   0  _0_
+```
+So, the next value of the third history is **`68`**.
+
+If you find the next value for each history in this example and add them together, you get **`114`**.
+
+Analyze your OASIS report and extrapolate the next value for each history. **What is the sum of these extrapolated 
+values**?

day09/src/main/resources/day09.txt

@@ -27,7 +27,10 @@ class Day09Test {
         @JvmStatic
         private fun getDataForTestSolvePart1(): Stream<Arguments> =
             Stream.of(
-                Arguments.of("part1sample1.txt", 0L)
+                Arguments.of("part1sample1.txt", 0L),
+                Arguments.of("part1sample2.txt", 0L),
+                Arguments.of("part1sample3.txt", 0L),
+                Arguments.of("part1sample4.txt", 0L)
             )
 
         @JvmStatic

day09/src/test/kotlin/de/havox_design/aoc2023/day09/Day09Test.kt

@@ -0,0 +1 @@
+0 3 6 9 12 15

day09/src/test/resources/part1sample1.txt

@@ -0,0 +1 @@
+1 3 6 10 15 21

day09/src/test/resources/part1sample2.txt

@@ -0,0 +1 @@
+10 13 16 21 30 45

day09/src/test/resources/part1sample3.txt

@@ -0,0 +1,3 @@
+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45