수 이어 쓰기 2

#include <iostream> #include <string> #include <cmath> int N, k; long long table[11]; void io_faster() { std::ios_base::sync_with_stdio(false); std::cin.tie(0); std::cout.tie(0); } void input() { io_faster(); std::cin >> N >> k; table[1] = 9; for (int i = 2 ; i < 10 ; i++) table[i] = table[i - 1] + i * std::pow(10, i - 1) * 9; } void solve() { int ind,number, number_ind;//ind : 자리수, number : 몇번째 for (int i = 1 ; i < 10 ; i++) { ind = i; if (k <= table[i]) break; } number = std::pow(10, (ind - 1)) + (int)((k - table[ind - 1] - 1) / ind); number_ind = (int)(k - table[ind - 1] - 1) % ind; if (number > N) { std::cout << -1; return ; } std::cout << std::to_string(number)[number_ind]; } int main() { input(); solve(); return (0); }