leetcode/src/s0038_count_and_say.cpp

#include "s0038_count_and_say.hpp"

string S0038::countAndSay(int n) {
  if (n == 1) {
    return "1";
  } else if (n <= 0) {
    return "";
  }
  string prev = countAndSay(n - 1);
  string result{""};
  int len = prev.length();
  int pos{0}, start{0};
  while (pos < len) {
    while (pos < len && prev[pos] == prev[start]) {
      pos++;
    }
    result += to_string(pos - start) + prev[start];
    start = pos;
  }
  return result;
}