题解 | #字符串加密#

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

using namespace std;

int main() {
  std::string secret;
  std::string info;

  cin >> secret;
  cin.ignore();
  cin >> info;

  // 处理密钥, 剔除重复的字符
  std::set<char> cc;
  std::string new_secret;
  for (char c : secret) {
    if (auto it = cc.find(c) == cc.end()) {
      new_secret.push_back(c);
      cc.insert(c);
    }
  }

  // 补充字母表
  char i = 'a';
  do {
    if (auto it = cc.find(i) == cc.end()) {
      new_secret.push_back(i);
    }
    i++;
  } while (i <= 'z');

  // 对明文里的每个字符查字母表
  std::string ret;
  for (char c : info) {
    int idx = c - 'a';
    ret += new_secret[idx];
  }

  std::cout << ret << std::endl;

  return 0;
}