Question

How to check if a sequence of numbers is a Harmonic progression (reciprocals Arithmetic progression) in C++

Answer 1

// a, b, c, d are HP if 1/a, 1/b, 1/c, 1/d are AP -> 1/a, 1/(a+diff), 1/(a+2*diff)...

#include <iostream>

int isHarmonicProgression(double arr[], int size) {
    if (size < 2) return 1;

    double diff = (1.0 / arr[1]) - (1.0 / arr[0]);

    for (int i = 2; i < size; i++) {
        if ((1.0 / arr[i]) - (1.0 / arr[i - 1]) != diff) {
            return 0; 
        }
    }
    
    return 1; 
}

int main() {
    double arr[] = {1.0 / 5, 1.0 / 10, 1.0 / 15, 1.0 / 20, 1.0 / 25}; 
    int size = sizeof(arr) / sizeof(arr[0]);

    (isHarmonicProgression(arr, size)) ? (std::cout << "Yes") : (std::cout << "No");
}



/*
run:

Yes

*/

 

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