#include "offer_58.hpp"

void Offer58::reverseSubStr(string &s, int begin, int end) {
  for (; begin < end; ++begin, --end) {
    char tmp = s[begin];
    s[begin] = s[end];
    s[end] = tmp;
  }
}

string Offer58::reverseLeftWords(string s, int n) {
  int len = s.length();
  reverseSubStr(s, 0, n - 1);
  reverseSubStr(s, n, len - 1);
  reverseSubStr(s, 0, len - 1);
  return s;
}