/* Author : ~swim~ Created : 27-Apr-2018 Description: [ASSIGNMENT] Betrothed numbers (quasi-amicable numbers) Betrothed numbers are two positive integers such that the sum of the proper divisors of either number is one more than the value of the other number. The first few pairs of Betrothed numbers are: (48, 75), (140, 195), (1050, 1925), (1575, 1648), (2024, 2295), (5775, 6128). TASK 1: Check if two given by user numbers are Betrothed numbers. Input: 48 75 Output: True TASK 2: Print out all pairs of Betrothed numbers in a range from 1 to some limit given by user. Input: 200 Output: (48, 75), (140, 195) Input : Enter 4 positive numbers separated by space or line where num1 = first number of the pair num2 = second number of the pair num3 = the limit for range in which to search for betrothed pairs num4 = step for generic betrothed pair. Step=1 for commonly known betrothed pair and press submit Note the pair will be checked if they are betrothed pair with N where N = step */ #include #include using ull = long long; using namespace std; constexpr inline ull sum_divisors(ull num) { ull sum{}; for(ull i{1}, half{(num/2)+1}; i<=half; ++i) sum += (num%i==0 ? i : 0); return sum; } void find_betrothed_list( ull ub, ull N=1) { // storage for betrothed pair list vector>betrothed_lst; for(ull i{48}; i<=ub; i++) { ull sumdi = sum_divisors(i); ull j = sumdi-N; ull sumdj = sum_divisors(j); // to avoid the duplicates and // ensure the pair is in the // range if(sumdj == i+N && ((i < j) && j<=ub)) betrothed_lst.emplace_back( make_pair(i,j)); }// end for if(betrothed_lst.size() > 0) { cout << "The list of betrothed" " numbers in the range[1," << ub << "] with" " step = " << N << " are :\n"; for(auto&& e: betrothed_lst) { cout << "(" << e.first << "," << e.second << ")" << " "; } }//end if(betrothed_lst.size() > 0) else { cout << "No betrothed pair in " "the\n" << "range[1," << ub << "] with step = " << N << "\n"; } } int main() { ull num1, num2; ull bound;//limit for the range // step=1 for commonly known // betrothed numbers ull step{1}; std::cin >> num1 >> num2 >> bound >> step; if(bound < 0 || step < 0) { cout << "error, bound or step" " cannot be < 0\n"; return -1; } cout << std::boolalpha << "is pair (" << num1 << "," << num2 << ") betrothed with step = " << step << " ?: " << (num1 == num2 ? false : (sum_divisors(num1) == num2+step && sum_divisors(num2) == num1+step)) << "\n\n"; // list of betrothed number pair // from 1 to limit entered by user // with step = step find_betrothed_list(bound, step); }// end main

[Assignment] Betrothed_numbers.cpp