C Exercises: Check if a given integer is a power of three

Last update on August 07 2025 12:49:18 (UTC/GMT +8 hours)

13. Power of Three Check Variants

Write a C program to check if a given integer is a power of three.

Example:
Input: 9
Output: true
Input: 81
Output: true
Input: 45
Output: false

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>
#include <stdbool.h>

// Function to check if a number is a power of three
static bool is_PowerOf_Three(int n) {
#if 0 // Alternative approach using recursive function
    if (n == 1) return true; // Base case: If n is 1, it is a power of three
    if (n == 0 || n % 3) return false; // If n is not divisible by 3 or is 0, it is not a power of three
    return is_PowerOf_Three(n / 3); // Recursively check if n divided by 3 is a power of three
#else // Optimized approach using mathematical property
    return (n > 0 && (1162261467 % n) == 0); // Return true if n is greater than 0 and 1162261467 is divisible by n
#endif
}

// Main function to test the is_PowerOf_Three function with different numbers
int main(void) {
    int n = 9;
    printf("\nIf %d is a power of three? %d", n, is_PowerOf_Three(n));
    n = 81;
    printf("\n\nIf %d is a power of three? %d", n, is_PowerOf_Three(n));
    n = 45;
    printf("\n\nIf %d is a power of three? %d", n, is_PowerOf_Three(n));
    return 0;
}

Sample Output:

If 9 is power of three? 1

If 81 is power of three? 1

If 45 is power of three? 0

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to determine if an integer is a power of three using logarithmic functions.
• Write a C program to check if a number is a power of three by iterative division until reaching one.
• Write a C program to verify the power-of-three property without loops by using recursion.
• Write a C program to test the power of three condition while handling negative and zero inputs appropriately.

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