不大于 N 且不包含 S 中任何数字的最大数字

#include <iostream>
#include <string>
#include <vector>

// function to check whether value stored in ‘i’ is part of string S while also converting S into integer data type.
bool attendance(int i, std::string s) {
   while (i) {
      int first_digit = i % 10;
      i /= 10;
      int t = std::stoi(s);
      bool found = false;
      while (t) {
         int second_digit = t % 10;
         t /= 10;
         if (second_digit == first_digit) {
            found = true;
            break;
         }
      }
      if (!found)
         return false;
   }
   return true;
}

// function to input two strings and check for each value less than N with all digits present in S.
std::string LargestNumberFinder(std::string x, std::string s) {
   int N = std::stoi(x);
   for (int i = N; i >= 1; i--) {
      if (attendance(i, s)) {
         return std::to_string(i);
      }
   }
   return "-1";
}

// main function to declare the variables and call the function.
int main() {
   std::string N = "100709";
   std::string S = "70";
   std::cout << LargestNumberFinder(N, S);
}

#include <iostream>
#include <string>
#include <vector>

using namespace std;

// function to check for all values of String N with String S and replacing the digit if found same with the largest possible digit not present in S.
string LargestNumberFinder(string num, string s) {
   vector<bool> vis_s(10, false);
   for (int i = 0; i < (int)s.size(); i++) {
      vis_s[int(s[i]) - 48] = true;
   }
   int n = num.size();
   int in = -1;
   for (int i = 0; i < n; i++) {
      if (vis_s[(int)num[i] - '0']) {
         in = i;
         break;
      }
   }
   if (in == -1) {
      return num;
   }
   for (char dig = num[in]; dig >= '0'; dig--) {
      if (vis_s[(int)dig - '0'] == 0) {
         num[in] = dig;
         break;
      }
   }
   char LargestDig = '0';
   for (char dig = '9'; dig >= '0'; dig--) {
      if (vis_s[dig - '0'] == false) {
         LargestDig = dig;
         break;
      }
   }
   for (int i = in + 1; i < n; i++) {
      num[i] = LargestDig;
   }
   int Count = 0;
   for (int i = 0; i < n; i++) {
      if (num[i] == '0')
         Count++;
      else
         break;
   }
   num.erase(0, Count);
   if ((int)num.size() == 0)
      return "0";
   return num;
}
int main() {
   string N = "161516";
   string S = "756";
   cout << LargestNumberFinder(N, S);
   return 0;
}