Wrote program for Day 64

README.md

@@ -110,7 +110,7 @@ We encourage you to share your progress and ask questions in the Discussions sec
 | Day #61       | [Write A Web Crawler](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-09/Day-61_Write-A-Web-Crawler)                   | :white_check_mark:      |
 | Day #62       | [Funny Plant](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-09/Day-62_Funny-Plant)                           | :white_check_mark:      |
 | Day #63       | [The Rabbit Problem](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-09/Day-63_The-Rabbit-Problem)                    | :white_check_mark:      |
-| Day #64       | [First Recurring Character](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-10/Day-64_First-Recurring-Character)             | :white_large_square:      |
+| Day #64       | [First Recurring Character](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-10/Day-64_First-Recurring-Character)             | :white_check_mark:      |
 | Day #65       | [ISBN Validator](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-10/Day-65_ISBN-Validator)                        | :white_large_square:      |
 | Day #66       | [ISBN Generator](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-10/Day-66_ISBN-Generator)                        | :white_large_square:      |
 | Day #67       | [Color Maze](https://github.com/LiveGray/100-Days-Of-Rust/tree/main/Week-10/Day-67_Color-Maze)                            | :white_large_square:      |

Week-10/Day-64_First-Recurring-Character/day64/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day64"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

Week-10/Day-64_First-Recurring-Character/day64/src/lib.rs

@@ -0,0 +1,12 @@
+use std::collections::HashMap;
+
+pub fn recurring_character(string: &str) -> Option<char> {
+    let mut chars = HashMap::new();
+    for c in string.chars() {
+        if chars.contains_key(&c) {
+            return Some(c);
+        }
+        chars.entry(c).or_insert(());
+    }
+    None
+}

Week-10/Day-64_First-Recurring-Character/day64/src/main.rs

@@ -0,0 +1,14 @@
+use std::io::{self, Write};
+
+use day64::recurring_character;
+
+fn main() {
+    let mut buffer = String::new();
+    print!("Enter a string to find its first recurring character: ");
+    io::stdout().flush().unwrap();
+    io::stdin().read_line(&mut buffer).unwrap();
+    match recurring_character(buffer.trim()) {
+        Some(x) => println!("The first recurring character is '{x}'"),
+        None => println!("The characters are all different from each other"),
+    }
+}

Week-10/Day-64_First-Recurring-Character/day64/tests/examples.rs

@@ -0,0 +1,14 @@
+#[cfg(test)]
+mod examples {
+    use day64::recurring_character;
+
+    #[test]
+    fn example1() {
+        assert_eq!(recurring_character("ABCDEBC"), Some('B'));
+    }
+
+    #[test]
+    fn example2() {
+        assert_eq!(recurring_character("ABBA"), Some('B'));
+    }
+}