From a7e7dab83ebb5a30a5ee7f2f9021ca72d90499e2 Mon Sep 17 00:00:00 2001
From: Mariano Riefolo <rfmariano@protonmail.com>
Date: Tue, 3 Sep 2024 11:26:54 +0200
Subject: [PATCH] Wrote program for Day 40

---
 README.md                                     |  2 +-
 Week-06/Day-40_Larrys-Array/day40/Cargo.toml  |  6 +++
 Week-06/Day-40_Larrys-Array/day40/src/lib.rs  | 35 ++++++++++++++++
 Week-06/Day-40_Larrys-Array/day40/src/main.rs | 41 +++++++++++++++++++
 .../day40/tests/example.rs                    |  9 ++++
 5 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 Week-06/Day-40_Larrys-Array/day40/Cargo.toml
 create mode 100644 Week-06/Day-40_Larrys-Array/day40/src/lib.rs
 create mode 100644 Week-06/Day-40_Larrys-Array/day40/src/main.rs
 create mode 100644 Week-06/Day-40_Larrys-Array/day40/tests/example.rs

diff --git a/README.md b/README.md
index 4687673..e9682ef 100644
--- a/README.md
+++ b/README.md
@@ -86,7 +86,7 @@ We encourage you to share your progress and ask questions in the Discussions sec
 | Day #37       | [Breaking The Records](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-37_Breaking-The-Records)                  | :white_check_mark:      |
 | Day #38       | [Electronics Shop](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-38_Electronics-Shop)                      | :white_check_mark:      |
 | Day #39       | [Halloween Sale](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-39_Halloween-Sale)                        | :white_check_mark:      |
-| Day #40       | [Larrys Array](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-40_Larrys-Array)                          | :white_large_square:      |
+| Day #40       | [Larrys Array](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-40_Larrys-Array)                          | :white_check_mark:      |
 | Day #41       | [Sales By Match](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-41_Sales-By-Match)                        | :white_large_square:      |
 | Day #42       | [Drawing Book](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-06/Day-42_Drawing-Book)                          | :white_large_square:      |
 | Day #43       | [Area Of A Triangle](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-07/Day-43_Area-Of-A-Triangle)                    | :white_large_square:      |
diff --git a/Week-06/Day-40_Larrys-Array/day40/Cargo.toml b/Week-06/Day-40_Larrys-Array/day40/Cargo.toml
new file mode 100644
index 0000000..b63e9e8
--- /dev/null
+++ b/Week-06/Day-40_Larrys-Array/day40/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "day40"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/Week-06/Day-40_Larrys-Array/day40/src/lib.rs b/Week-06/Day-40_Larrys-Array/day40/src/lib.rs
new file mode 100644
index 0000000..eea4887
--- /dev/null
+++ b/Week-06/Day-40_Larrys-Array/day40/src/lib.rs
@@ -0,0 +1,35 @@
+fn rotate(array: &mut [usize], start: usize) {
+    array.swap(start, start + 1);
+    array.swap(start + 1, start + 2);
+}
+
+pub fn larry_array(mut array: Vec<usize>) -> Result<bool, String> {
+    let mut next = 1;
+
+    while next <= array.len() {
+        let mut index = match array.iter().position(|&e| e == next) {
+            Some(x) => x,
+            None => {
+                return Err(
+                    "The array must contains all the numbers from 1 to the array's length"
+                        .to_owned(),
+                );
+            }
+        };
+
+        if index != next - 1 && next == array.len() - 1 {
+            return Ok(false);
+        }
+
+        while index != next - 1 {
+            let start = std::cmp::max(index - 2, next - 1);
+            let end = start + 2;
+            rotate(&mut array, start);
+            index = (end + index - 1) % end;
+        }
+
+        next += 1;
+    }
+
+    Ok(true)
+}
diff --git a/Week-06/Day-40_Larrys-Array/day40/src/main.rs b/Week-06/Day-40_Larrys-Array/day40/src/main.rs
new file mode 100644
index 0000000..a9f75dd
--- /dev/null
+++ b/Week-06/Day-40_Larrys-Array/day40/src/main.rs
@@ -0,0 +1,41 @@
+use std::{
+    io::{self, Write},
+    process::exit,
+};
+
+use day40::larry_array;
+
+fn main() {
+    print!("Insert the Larry's array (space separated numbers from 1 to the #numbers): ");
+    io::stdout().flush().expect("Failed to flush stdout");
+
+    let mut buffer = String::new();
+    io::stdin()
+        .read_line(&mut buffer)
+        .expect("Failed to read line");
+
+    let array = buffer
+        .split_whitespace()
+        .map(|x| match x.parse() {
+            Ok(x) => x,
+            Err(e) => {
+                eprintln!("{e}");
+                exit(1);
+            }
+        })
+        .collect();
+
+    match larry_array(array) {
+        Ok(x) => {
+            if x {
+                println!("The array can be sorted!");
+            } else {
+                println!("The array cannot be sorted!");
+            }
+        }
+        Err(e) => {
+            eprintln!("{e}");
+            exit(1);
+        }
+    };
+}
diff --git a/Week-06/Day-40_Larrys-Array/day40/tests/example.rs b/Week-06/Day-40_Larrys-Array/day40/tests/example.rs
new file mode 100644
index 0000000..ae52841
--- /dev/null
+++ b/Week-06/Day-40_Larrys-Array/day40/tests/example.rs
@@ -0,0 +1,9 @@
+#[cfg(test)]
+mod example {
+    use day40::larry_array;
+
+    #[test]
+    fn example() {
+        assert_eq!(larry_array(vec![1, 6, 5, 2, 4, 3]), Ok(true));
+    }
+}