SRM405 Div1Easy RelativePath

解法
先にstringの階層構造をvector化すると扱いやすくなる。

class RelativePath {
public:
  
  vector<string> make(string str) {
    int N = str.size();
    for(int i=0; i<N; i++) {
      if(str[i] == '/') { str[i] = ' '; }
    }
    stringstream ss(str);
    vector<string> ret;
    ret.push_back("ROOT");
    while(ss >> str) ret.push_back(str);
    return ret;
  }
  
  string makeRelative(string path, string currentDir) {
    vector<string> Path = make(path);
    vector<string> CDir = make(currentDir);
    
    int same = 0;
    for(int i=0; i<min(Path.size(), CDir.size()); i++, same ++) {
      if(Path[i]!=CDir[i]) { break; }
    }
    
    string ret;
    while(same < CDir.size()) {
      CDir.pop_back();
      ret += "../";
    }
    for(int i=same; i<Path.size(); i++) {
      ret += Path[i] + "/";
    }
    ret.pop_back();
    return ret;
  }
};