rmvdup

#include <iostream>
#include <fstream>
#include <set>
using namespace std;


typedef set<string> ss_t;
ss_t ipSet;


void process(char* iname, char* oname)
{
    // NlogN
    ifstream fin(iname);
    string ip;
    while (fin >> ip) ipSet.insert(ip);
    fin.close();
    ofstream fout(oname);
    for (ss_t::iterator it = ipSet.begin(); it != ipSet.end(); ++it) fout << *it << '\n';
    fout.close();
}


int main(int argc, char* argv[])
{
    if (argc != 3) {
        cout << "Usage: " << argv[0] << " infile outfile" << endl;
    } else {
        process(argv[1], argv[2]);
    }
    return 0;
}