Wrote program for Day 29

I suppose that the fourth example returns an error because the input is
too short

README.md

@@ -75,7 +75,7 @@ We encourage you to share your progress and ask questions in the Discussions sec
 | Day #26       | [Briefcase Lock](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-04/Day-26_Briefcase-Lock)                        | :white_check_mark:      |
 | Day #27       | [Task Scheduler](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-04/Day-27_Task-Scheduler)                        | :white_check_mark:      |
 | Day #28       | [Word Search](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-04/Day-28_Word-Search)                           | :white_check_mark:      |
-| Day #29       | [Traffic Light Checker](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-05/Day-29_Traffic-Light-Checker)                 | :white_large_square:      |
+| Day #29       | [Traffic Light Checker](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-05/Day-29_Traffic-Light-Checker)                 | :white_check_mark:      |
 | Day #30       | [The Maximum Value](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-05/Day-30_The-Maximum-Value)                     | :white_large_square:      |
 | Day #31       | [The Time In Words](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-05/Day-31_The-Time-In-Words)                     | :white_large_square:      |
 | Day #32       | [Climbing The Leaderboard](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-05/Day-32_Climbing-The-Leaderboard)              | :white_large_square:      |

Week-05/Day-29_Traffic-Light-Checker/day29/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day29"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

Week-05/Day-29_Traffic-Light-Checker/day29/src/lib.rs

@@ -0,0 +1,58 @@
+pub fn tl_checker(lights: &[char]) -> TLR {
+    if lights.len() < 4 || lights.len() > 15 {
+        return TLR::Error;
+    }
+
+    let mut previous = &'X';
+
+    for light in lights {
+        if !matches!(light, 'R' | 'Y' | 'G' | 'P' | 'C') {
+            return TLR::Error;
+        }
+
+        match previous {
+            'R' => {
+                if !matches!(light, 'G' | 'P' | 'C') {
+                    return TLR::Reject;
+                }
+            }
+            'Y' => {
+                if light != &'R' {
+                    return TLR::Reject;
+                }
+            }
+            'G' => {
+                if light != &'Y' {
+                    return TLR::Reject;
+                }
+            }
+            'P' => {
+                if light != &'R' {
+                    return TLR::Reject;
+                }
+            }
+            'C' => {
+                if light != &'R' {
+                    return TLR::Reject;
+                }
+            }
+            'X' => {
+                if light != &'R' {
+                    return TLR::Reject;
+                }
+            }
+            _ => return TLR::Error,
+        }
+
+        previous = light;
+    }
+
+    TLR::Accept
+}
+
+#[derive(Debug, PartialEq)]
+pub enum TLR {
+    Accept,
+    Reject,
+    Error,
+}

Week-05/Day-29_Traffic-Light-Checker/day29/src/main.rs

@@ -0,0 +1,23 @@
+use std::io::{self, Write};
+
+use day29::tl_checker;
+
+fn main() {
+    let mut buffer = String::new();
+
+    print!("Enter the traffic light sequence: ");
+    io::stdout().flush().expect("Failed to flush stdout");
+
+    io::stdin()
+        .read_line(&mut buffer)
+        .expect("Failed to read the sequence");
+
+    let sequence: Vec<char> = buffer.chars().filter(|c| !c.is_whitespace()).collect();
+
+    let result = tl_checker(&sequence);
+    match result {
+        day29::TLR::Accept => println!("The sequence is accepted"),
+        day29::TLR::Reject => println!("The sequence is rejected"),
+        day29::TLR::Error => println!("The sequence is invalid"),
+    }
+}

Week-05/Day-29_Traffic-Light-Checker/day29/tests/examples.rs

@@ -0,0 +1,42 @@
+#[cfg(test)]
+mod examples {
+    use day29::{tl_checker, TLR};
+
+    #[test]
+    fn example1() {
+        assert_eq!(
+            tl_checker(&['R', 'G', 'Y', 'R', 'C', 'R', 'G', 'Y', 'R']),
+            TLR::Accept
+        );
+    }
+
+    #[test]
+    fn example2() {
+        assert_eq!(tl_checker(&['G', 'Y', 'R', 'G', 'Y', 'R']), TLR::Reject);
+    }
+
+    #[test]
+    fn example3() {
+        assert_eq!(tl_checker(&['R', 'Y', 'G', 'P']), TLR::Reject);
+    }
+
+    #[test]
+    fn example4() {
+        assert_eq!(tl_checker(&['R', 'G', 'Y']), TLR::Error);
+    }
+
+    #[test]
+    fn example5() {
+        assert_eq!(tl_checker(&['X', '8', 'S']), TLR::Error);
+    }
+
+    #[test]
+    fn example6() {
+        assert_eq!(
+            tl_checker(&[
+                'R', 'G', 'Y', 'R', 'C', 'R', 'P', 'R', 'G', 'Y', 'R', 'G', 'Y', 'R', 'G', 'Y', 'R'
+            ]),
+            TLR::Error
+        );
+    }
+}