Add problem 0326: Power of Three

src/lib.rs

@@ -292,6 +292,7 @@ pub mod problem_0304_range_sum_query_2d_immutable;
 pub mod problem_0307_range_sum_query_mutable;
 pub mod problem_0316_remove_duplicate_letters;
 pub mod problem_0322_coin_change;
+pub mod problem_0326_power_of_three;
 pub mod problem_0331_verify_preorder_serialization_of_a_binary_tree;
 pub mod problem_0338_counting_bits;
 pub mod problem_0341_flatten_nested_list_iterator;

src/problem_0326_power_of_three/math.rs

@@ -0,0 +1,23 @@
+pub struct Solution;
+
+impl Solution {
+    pub fn is_power_of_three(n: i32) -> bool {
+        // 3^19 < i32::MAX
+        // 3^20 > i32::MAX
+        n > 0 && (1_162_261_467 % n == 0)
+    }
+}
+
+impl super::Solution for Solution {
+    fn is_power_of_three(n: i32) -> bool {
+        Self::is_power_of_three(n)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_0326_power_of_three/mod.rs

@@ -0,0 +1,18 @@
+pub mod math;
+
+pub trait Solution {
+    fn is_power_of_three(n: i32) -> bool;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [(27, true), (0, false), (9, true), (45, false)];
+
+        for (n, expected) in test_cases {
+            assert_eq!(S::is_power_of_three(n), expected);
+        }
+    }
+}