Wrote program for Day 8

Week-02/Day-08_Letter-Combinations-Of-A-Phone-Number/day8/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day8"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

Week-02/Day-08_Letter-Combinations-Of-A-Phone-Number/day8/src/lib.rs

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+fn digit_to_chars(digit: char) -> Vec<char> {
+    match digit {
+        '2' => vec!['a', 'b', 'c'],
+        '3' => vec!['d', 'e', 'f'],
+        '4' => vec!['g', 'h', 'i'],
+        '5' => vec!['j', 'k', 'l'],
+        '6' => vec!['m', 'n', 'o'],
+        '7' => vec!['p', 'q', 'r', 's'],
+        '8' => vec!['t', 'u', 'v'],
+        '9' => vec!['w', 'x', 'y', 'z'],
+        _ => panic!(
+            "Character out of range: '{}' is not between '2' and '9'.",
+            digit
+        ),
+    }
+}
+
+pub fn combination(digits: &str) -> Vec<String> {
+    let mut combinations: Vec<String> = vec![String::new()];
+
+    for d in digits.chars() {
+        let mut temp = Vec::new();
+        for c in combinations {
+            let chars = digit_to_chars(d);
+            for ch in chars {
+                temp.push(format!("{}{}", c, ch));
+            }
+        }
+        combinations = temp;
+    }
+
+    if combinations.len() == 1 {
+        vec![] as Vec<String>
+    } else {
+        combinations
+    }
+}

Week-02/Day-08_Letter-Combinations-Of-A-Phone-Number/day8/src/main.rs

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+use std::io::{self, Write};
+
+use day8::combination;
+
+fn main() {
+    let mut buffer = String::new();
+
+    print!("Insert the digits: ");
+    io::stdout().flush().expect("Failed to flush stdout.");
+
+    io::stdin()
+        .read_line(&mut buffer)
+        .expect("Failed to read the digits.");
+
+    let combinations = combination(buffer.trim());
+
+    println!(
+        "Those are all the possible combinations: {:?}",
+        combinations
+    );
+}

Week-02/Day-08_Letter-Combinations-Of-A-Phone-Number/day8/tests/examples.rs

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+use day8::combination;
+
+#[test]
+fn example1() {
+    assert_eq!(
+        combination("23"),
+        vec!["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]
+    );
+}
+
+#[test]
+fn example2() {
+    assert_eq!(combination(""), vec![] as Vec<String>);
+}
+
+#[test]
+fn example3() {
+    assert_eq!(combination("2"), vec!["a", "b", "c"]);
+}