// Given a list of numbers of length n, this routine extracts a // longest increasing subsequence. // // Running time: O(n log n) // // INPUT: a vector of integers // OUTPUT: a vector containing the longest increasing subsequence #include #include #include using namespace std; typedef vector VI; typedef pair PII; typedef vector VPII; #define STRICTLY_INCREASNG VI LongestIncreasingSubsequence(VI v) { VPII best; VI dad(v.size(), -1); for (int i = 0; i < v.size(); i++) { #ifdef STRICTLY_INCREASNG PII item = make_pair(v[i], 0); VPII::iterator it = lower_bound(best.begin(), best.end(), item); item.second = i; #else PII item = make_pair(v[i], i); VPII::iterator it = upper_bound(best.begin(), best.end(), item); #endif if (it == best.end()) { dad[i] = (best.size() == 0 ? -1 : best.back().second); best.push_back(item); } else { dad[i] = dad[it->second]; *it = item; } } VI ret; for (int i = best.back().second; i >= 0; i = dad[i]) ret.push_back(v[i]); reverse(ret.begin(), ret.end()); return ret; }