Fine-tuning CodeLlama-7B for Fortran Code Generation

Given an integer n, return true if it is a power of four. Otherwise, return false.

An integer n is a power of four, if there exists an integer x such that n == 4x.

Example 1:

Input: n = 16 Output: true

Example 2:

Input: n = 5 Output: false

Example 3:

Input: n = 1 Output: true

Constraints:

-231 <= n <= 231 - 1

Follow up: Could you solve it without loops/recursion?

Note: This problem is from LeetCode.

❌ Compiled

❌ Executed

❌ Correct

program main
    implicit none

    integer :: n
    logical :: result

    ! Example 1: 16
    n = 16
    result = is_power_of_four(n)
    print '(L1)', result

    ! Example 2: 5
    n = 5
    result = is_power_of_four(n)
    print '(L1)', result

    ! Example 3: 1
    n = 1
    result = is_power_of_four(n)
    print '(L1)', result

contains

    function is_power_of_four(n) result(result)
        implicit none
        integer, intent(in) :: n
        logical :: result
        integer :: x

        result = .false.
        do while (n > 0)
            x = n / 4
            if (x * 4 == n) then
                result = .true.
                exit
            end if
            n = x
        end do
    end function is_power_of_four

end program main

stderr

temp.f95:37:12:

   37 |             n = x
      |            1
Error: Dummy argument ‘n’ with INTENT(IN) in variable definition context (assignment) at (1)

✅ Compiled

✅ Executed

⚠️ Correct

module power_of_four
implicit none
private
public :: is_power_of_four

contains

function is_power_of_four(n) result(is_four)
integer, intent(in) :: n
logical :: is_four
integer :: x

is_four = .false.
if (n < 1) return

x = 4
do while (x <= n)
    if (n == x) then
        is_four = .true.
        exit
    end if
    x = x * 4
end do

end function is_power_of_four
end module power_of_four

program power_of_four_test
use power_of_four, only : is_power_of_four
implicit none
integer :: n

n = 16
write (*,*) 'n = ', n, 'is power of four: ', is_power_of_four(n)

n = 5
write (*,*) 'n = ', n, 'is power of four: ', is_power_of_four(n)

n = 1
write (*,*) 'n = ', n, 'is power of four: ', is_power_of_four(n)

n = -231
write (*,*) 'n = ', n, 'is power of four: ', is_power_of_four(n)

n = 231 - 1
write (*,*) 'n = ', n, 'is power of four: ', is_power_of_four(n)

end program power_of_four_test

stdout

 n =           16 is power of four:  T
 n =            5 is power of four:  F
 n =            1 is power of four:  F
 n =         -231 is power of four:  F
 n =          230 is power of four:  F

🌐 Data from online sources

def isPowerOfFour(n: int) -> bool:
    if n <= 0:
        return False
    while n % 4 == 0:
        n //= 4
    return n == 1

The algorithm checks if a given integer n is a power of 4 or not. If n is less than or equal to 0, it immediately returns false. Otherwise, it enters a loop that checks if n is divisible by 4. If it is, it keeps dividing the number by 4 until it is no longer divisible by 4. After the loop, the algorithm checks whether the final remainder is 1 or not. If the remainder is 1, the number was initially a power of 4, and it returns true. Otherwise, it returns false.

🌐 Data from online sources

bool isPowerOfFour(int n) {
    if (n <= 0) return false;
    while (n % 4 == 0) {
        n /= 4;
    }
    return n == 1;
}

Power of Four