INIT: task2

hw1/task2/README.md

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+# Homework hw1 task 2
+
+## prepare your task
+
+Run `cargo init` in your `task2/` directory.
+
+## task
+
+Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
+
+There once was a wise servant who saved the life of a prince. The king
+promised to pay whatever the servant could dream up. Knowing that the
+king loved chess, the servant told the king he would like to have grains
+of wheat. One grain on the first square of a chess board. Two grains on
+the next. Four on the third, and so on.
+
+There are 64 squares on a chessboard.
+
+Write code that shows:
+
+- how many grains were on each square (`fn square(n: u32) -> u64`), and
+- the total number of grains (`fn total() -> u64`)
+
+Use the given file `lib.rs` for your solution.

hw1/task2/src/lib.rs

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+pub fn square(n: u32) -> u64 {
+    unimplemented!()
+}
+
+
+pub fn total() -> u64 {
+    unimplemented!();
+}

hw1/task2/tests/task2.rs

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+extern crate task2;
+
+#[test]
+fn square_one() {
+    assert_eq!(task2::square(1), 1);
+}
+
+#[test]
+fn square_two() {
+    assert_eq!(task2::square(2), 2);
+}
+
+#[test]
+fn square_three() {
+    assert_eq!(task2::square(3), 4);
+}
+
+#[test]
+fn square_four() {
+    assert_eq!(task2::square(4), 8);
+}
+
+#[test]
+fn square_sixteen() {
+    assert_eq!(task2::square(16), 32_768);
+}
+
+#[test]
+fn square_thirty_two() {
+    assert_eq!(task2::square(32), 2_147_483_648);
+}
+
+#[test]
+fn square_sixty_four() {
+    assert_eq!(task2::square(64), 9_223_372_036_854_775_808);
+}
+
+#[test]
+fn total_sums_all_squares() {
+    assert_eq!(task2::total(), 18_446_744_073_709_551_615);
+}