SRM 175 Div1 Level 2 Books

#include <algorithm>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
using namespace std;
typedef long long LL;
#define FOR(k,a,b) for(int k(a); k < (b); ++k)
#define REP(k,a) for(int k=0; k < (a); ++k)


class Books {
public:
    int sortMoves(vector <string> titles)
    {
        int n=titles.size();
        vector<pair<string,int> > tp(n);
        REP(i,n)
        {
            tp[i].first=titles[i];
            tp[i].second=i;
        }
        sort(tp.begin(),tp.end());
        vector<int> seq(n);
        REP(i,n)
            seq[i]=tp[i].second;
        //longest increasing seq
        vector<int> lis;
        vector<int>::iterator it;
        REP(i,n)
        {
            it=lower_bound(lis.begin(),lis.end(),seq[i]);
            if(it==lis.end())
                lis.push_back(seq[i]);
            else
                *it=seq[i];
        }
        return n-lis.size();
    }

};