Adding longest increasing subsequence in O(nlogn)

Author: bicycleman15

LIS_in_O(nlogn).cpp

@@ -0,0 +1,24 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+//Note that the below code works only for distinct longest increasing subsequence
+// If you want also want duplicate elements in LIS then change lower_bound to upper_bound and it will account for duplicates as well
+
+int main() {
+  int n;
+  cin >> n;
+  vector<int> dp;
+  
+  for (int i = 0; i < n; i++) {
+    int x;
+    cin >> x;
+    auto it = lower_bound(dp.begin(), dp.end(), x);
+    if (it == dp.end()) {
+      dp.push_back(x);
+    } else {
+      *it = x;
+    }
+  }
+  
+  cout << dp.size() << endl;
+}