uva12504 Updating a Dictionary

#include<iostream>#include<string>#include<sstream>#include<cctype>#include<map>#include<vector>#include<algorithm>using namespace std;void make_dict(string s, map<string,string>& m, vector<string>& keys) {  for(int i = 0; i < s.size(); i++) {    if(!isalpha(s[i]) && !isdigit(s[i])) s[i] = ' ';  }  stringstream ss(s);  string key, value;  while(ss >> key) {    ss >> value;    m[key] = value;    keys.push_back(key);  }}void print_list(const vector<string> v) {  for(int i = 0; i < v.size(); i++) {    if(i != 0) cout << ',';    cout << v[i];  }  cout << '\n';}int main() {  int T;  cin >> T;  while(T--) {    string d1, d2;    map<string,string> m1, m2;    vector<string> all, added, removed, changed;    cin >> d1 >> d2;    make_dict(d1, m1, all);    make_dict(d2, m2, all);    sort(all.begin(), all.end());    all.erase(unique(all.begin(), all.end()), all.end());    for(int i = 0; i < all.size(); i++) {      string key = all[i];      if(!m1.count(key) && m2.count(key)) added.push_back(key);      if(m1.count(key) && !m2.count(key)) removed.push_back(key);      if(m1.count(key) && m2.count(key) && m1[key] != m2[key]) changed.push_back(key);    }    int flag = 0;    if(!added.empty()) { flag = 1; cout << "+"; print_list(added); }    if(!removed.empty()) { flag = 1; cout << "-"; print_list(removed); }    if(!changed.empty()) { flag = 1; cout << "*"; print_list(changed); }    if(!flag) cout << "No changes\n";    cout << "\n";  }  return 0;}