题解 | #字符串变形#

class Solution {
public:
  string trans(string s, int n) {
    // write code here
    string tmp, ret;
    for (int i = n - 1; i >= 0; --i) {
      char ch;
      if (s[i] >= 'a' && s[i] <= 'z') {
        ch = s[i] - 32;
      } else if (s[i] >= 'A' && s[i] <= 'Z') {
        ch = s[i] + 32;
      } else {
        tmp.push_back(s[i]);
        ret.insert(ret.length(), tmp);
        tmp.clear();
        continue;
      }
      tmp.insert(0, 1, ch);
    }
    if (!tmp.empty()) {
        ret.insert(ret.length(), tmp);
        tmp.clear();
    }
    return ret;
  }
};