Add assignment 2

src/assignments/assignment02.rs

@@ -1,3 +1,141 @@
 //! Assignment 2: Mastering common programming concepts (1/2).
+//!
+//! The primary goal of this assignment is to re-learn the common programming concepts in Rust, especially those in the Rust Book chapters 3 and 5.
+//! Please make sure you're comfortable with the concepts to proceed on to the next assignments.
+//!
+//! You should fill out the `todo!()` placeholders in such a way that `/scripts/grade-02.sh` works fine.
+//! See `assignment02_grade.rs` and `/scripts/grade-02.sh` for the test script.
 
-// TODO: use exercises in <https://doc.rust-lang.org/book/ch03-05-control-flow.html>
+use std::ops::Mul;
+
+const FARHENHEIT_OFFSET: f64 = 32.0;
+const FARHENHEIT_SCALE: f64 = 5.0 / 9.0;
+
+/// Converts Farenheit to Celcius temperature degree.
+pub(crate) fn farhenheit_to_celcius(degree: f64) -> f64 {
+    todo!()
+}
+
+/// Captializes English alphabets (leaving the other characters intact).
+pub(crate) fn capitalize(input: String) -> String {
+    todo!()
+}
+
+/// Returns the sume of the given array. (We assume the absence of integer overflow.)
+pub(crate) fn sum_array(input: &[u64]) -> u64 {
+    todo!()
+}
+
+/// Given a non-negative integer, say `n`, return the smallest integer of the form `3^m` that's greater than or equal to `n`.
+///
+/// For instance, up3(6) = 9, up3(9) = 9, up3(10) = 27. (We assume the absence of integer overflow.)
+pub(crate) fn up3(n: u64) -> u64 {
+    todo!()
+}
+
+/// Returns the greatest common divisor (GCD) of two non-negative integers. (We assume the absence of integer overflow.)
+pub(crate) fn gcd(lhs: u64, rhs: u64) -> u64 {
+    todo!()
+}
+
+/// Returns the array of nC0, nC1, nC2, ..., nCn, where nCk = n! / (k! * (n-k)!).
+pub(crate) fn chooses(n: u64) -> Vec<u64> {
+    todo!()
+}
+
+/// Returns the "zip" of two vectors.
+///
+/// For instance, `zip(vec![1, 2, 3], vec![4, 5])` equals to `vec![(1, 4), (2, 5)]`.
+/// Here, `3` is ignored because it doesn't have a partner.
+pub(crate) fn zip(lhs: Vec<u64>, rhs: Vec<u64>) -> Vec<(u64, u64)> {
+    todo!()
+}
+
+/// 2x2 matrix of the following configuration:
+///
+/// a, b
+/// c, d
+#[derive(Debug, Clone, Copy)]
+struct Mat2 {
+    a: u64,
+    b: u64,
+    c: u64,
+    d: u64,
+}
+
+/// 2x1 matrix of the following configuration:
+///
+/// a
+/// b
+#[derive(Debug, Clone, Copy)]
+struct Vec2 {
+    a: u64,
+    b: u64,
+}
+
+impl Mat2 {
+    /// Creates an identity matrix.
+    fn new() -> Self {
+        Self {
+            a: 1,
+            b: 0,
+            c: 0,
+            d: 1,
+        }
+    }
+}
+
+impl Mul<Mat2> for Mat2 {
+    type Output = Mat2;
+
+    fn mul(self, rhs: Mat2) -> Self::Output {
+        todo!()
+    }
+}
+
+impl Mul<Vec2> for Mat2 {
+    type Output = Vec2;
+
+    fn mul(self, rhs: Vec2) -> Self::Output {
+        todo!()
+    }
+}
+
+impl Mat2 {
+    /// Calculates the power of matrix.
+    fn power(self, power: u64) -> Mat2 {
+        todo!()
+    }
+}
+
+impl Vec2 {
+    /// Gets the upper value of vector.
+    fn get_upper(self) -> u64 {
+        todo!()
+    }
+}
+
+/// The matrix used for calculating Fibonacci numbers.
+const FIBONACCI_MAT: Mat2 = Mat2 {
+    a: 1,
+    b: 1,
+    c: 1,
+    d: 0,
+};
+
+/// The vector used for calculating Fibonacci numbers.
+const FIBONACCI_VEC: Vec2 = Vec2 { a: 1, b: 0 };
+
+/// Calculates the Fibonacci number.
+///
+/// Consult <https://web.media.mit.edu/~holbrow/post/calculating-fibonacci-numbers-with-matrices-and-linear-algebra/> for matrix computation of Fibonacci numbers.
+pub(crate) fn fibonacci(n: u64) -> u64 {
+    (FIBONACCI_MAT.power(n) * FIBONACCI_VEC).get_upper()
+}
+
+/// Writes down the lyrics of "twelve days of christmas".
+///
+/// Hint: Google the song title for lyrics and look at the test code for the expected result.
+pub(crate) fn twelve_days_of_christmas_lyrics() -> String {
+    todo!()
+}