exercism/c/difference-of-squares/difference_of_squares.c

#include "difference_of_squares.h"

unsigned int sum_of_squares(unsigned int number) {

  unsigned sum = 0;
  for (unsigned i = 1; i <= number; i++) {
    sum += i * i;
  }
  return sum;
}

unsigned int square_of_sum(unsigned int number) {

  unsigned square = 0;
  for (unsigned i = 1; i <= number; i++) {
    square += i;
  }

  return square * square;
}

unsigned int difference_of_squares(unsigned int number) {

  return square_of_sum(number) - sum_of_squares(number);
}