1 // Convert a list of distinct elements to [0..N), preserving the original order. | 1 // Convert a list of N elements with K distinct elements to [origin .. origin+K) 2 // O(N log N), but doesn't incur the overhead of std::map. | 2 // preserving the original order. O(N log N), but doesn't incur the overhead of 3 // Tested: TCO 2012 R2C Mid | 3 // Tested: TCO 2012 R2C Mid, SRM 584 Mid 4 4 5 template<typename T> 5 template<typename T> 6 std::vector<int> compress(std::vector<T>& xs) | 6 vector<int> compress(const vector<T>& xs, int origin = 0) 7 { 7 { 8 std::vector< pair<T,int> > xi; | 8 vector< pair<T,int> > xi; 9 for(int i=0; i<xs.size(); ++i) 9 for(int i=0; i<xs.size(); ++i) 10 xi.push_back( make_pair(xs[i], i) ); 10 xi.push_back( make_pair(xs[i], i) ); 11 sort(xi.begin(), xi.end()); 11 sort(xi.begin(), xi.end()); 12 12 13 std::vector<int> result(xs.size()); | 13 vector<int> result(xs.size()); 14 for(int k=0; k<xi.size(); ++k) | 14 for(int k=0,id=origin; k<xi.size(); ++k) { > 15 if(0<=k-1 && xi[k-1].first<xi[k].first) > 16 ++id; 15 result[xi[k].second] = k; | 17 result[xi[k].second] = id; > 18 } 16 return result; 19 return result; 17 } 20 }