I need answer anyone knows please tell me

Question

Compute nearest larger number by interchanging digits updated. Given 2 numbers a and b find the smallest number greater than b by interchanging the digits of a and if not possible print -1. Constraints 1 <= a,b <= 10000000 Explanation Example 1

Input

459 500

Output

549

Answer 1

https://code.sololearn.com/c02exV7xZC14

#include <iostream>
#include <algorithm>
#include <string>

std::string nearestLargerNumber (std::string a, const std::string &b);

int main()
{
std::string strA {}, strB {};
std::cout << "Enter a and b seperated by a space: ";
std::cin >> strA >> strB;
std::cout << std::endl;
long long NLN = std::stoll (nearestLargerNumber(strA, strB));
if (NLN > std::stoll(strB))
std::cout << NLN << std::endl;
else
std::cout << -1 << std::endl;
return 0;
}

std::string nearestLargerNumber (std::string a, const std::string &b)
{
if (a.size() < b.size())
return a;
sort(a.begin(), a.end());
for (size_t i {}; i < b.size(); i++)
for (size_t j {i}; j < a.size(); j++)
if (a.at(j) >= b.at(i)) {
std::swap(a.at(j), a.at(i));
break;
}
return a;
}