Add another Perfect Cube implementation (TheAlgorithms#651)

DIRECTORY.md

@@ -199,6 +199,7 @@
  * [Newton Raphson](https://github.com/TheAlgorithms/Rust/blob/master/src/math/newton_raphson.rs)
  * [Nthprime](https://github.com/TheAlgorithms/Rust/blob/master/src/math/nthprime.rs)
  * [Pascal Triangle](https://github.com/TheAlgorithms/Rust/blob/master/src/math/pascal_triangle.rs)
+ * [Perfect Cube](https://github.com/TheAlgorithms/Rust/blob/master/src/math/perfect_cube.rs)
  * [Perfect Numbers](https://github.com/TheAlgorithms/Rust/blob/master/src/math/perfect_numbers.rs)
  * [Perfect Square](https://github.com/TheAlgorithms/Rust/blob/master/src/math/perfect_square.rs)
  * [Pollard Rho](https://github.com/TheAlgorithms/Rust/blob/master/src/math/pollard_rho.rs)

src/math/mod.rs

@@ -47,6 +47,7 @@ mod miller_rabin;
 mod newton_raphson;
 mod nthprime;
 mod pascal_triangle;
+mod perfect_cube;
 mod perfect_numbers;
 mod perfect_square;
 mod pollard_rho;
@@ -131,6 +132,7 @@ pub use self::miller_rabin::{big_miller_rabin, miller_rabin};
 pub use self::newton_raphson::find_root;
 pub use self::nthprime::nthprime;
 pub use self::pascal_triangle::pascal_triangle;
+pub use self::perfect_cube::{perfect_cube, perfect_cube_binary_search};
 pub use self::perfect_numbers::perfect_numbers;
 pub use self::perfect_square::perfect_square;
 pub use self::perfect_square::perfect_square_binary_search;

src/math/perfect_cube.rs

@@ -0,0 +1,55 @@
+pub fn perfect_cube(n: i32) -> bool {
+ // Calculate the cube root using floating-point arithmetic.
+ let val = (n as f64).powf(1.0 / 3.0);
+ // Check if the cube of the cube root equals the original number.
+ (val * val * val) == (n as f64)
+}
+
+// Check if a number is a perfect cube using binary search.
+pub fn perfect_cube_binary_search(n: i64) -> bool {
+ // Handle negative numbers, as cube roots are not defined for negatives.
+ if n < 0 {
+ return false;
+ }
+
+ // Initialize left and right boundaries for binary search.
+ let mut left = 0;
+ let mut right = n.abs(); // Use the absolute value to handle negative numbers
+
+ // Binary search loop to find the cube root.
+ while left <= right {
+ // Calculate the mid-point.
+ let mid = left + (right - left) / 2;
+ // Calculate the cube of the mid-point.
+ let cube = mid * mid * mid;
+
+ // Check if the cube equals the original number.
+ match cube.cmp(&n) {
+ std::cmp::Ordering::Equal => return true,
+ std::cmp::Ordering::Less => left = mid + 1,
+ std::cmp::Ordering::Greater => right = mid - 1,
+ }
+ }
+
+ // If no cube root is found, return false.
+ false
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn test_perfect_cube() {
+ assert!(perfect_cube_binary_search(27));
+ assert!(!perfect_cube_binary_search(4));
+ }
+
+ #[test]
+ fn test_perfect_cube_binary_search() {
+ assert!(perfect_cube_binary_search(27));
+ assert!(perfect_cube_binary_search(64));
+ assert!(!perfect_cube_binary_search(4));
+ assert!(!perfect_cube_binary_search(-8));
+ }
+}