Data Structure Array: Longest Monotonically Increasing Subsequence Size

http://www.geeksforgeeks.org/longest-monotonically-increasing-subsequence-size-n-log-n/

 1 #include <iostream>

 2 #include <vector>

 3 #include <algorithm>

 4 #include <queue>

 5 #include <stack>

 6 #include <string>

 7 #include <fstream>

 8 #include <map>

 9 using namespace std;

10 

11 int maxsum(int arr[], int n) {

12     vector<int> tail;

13     tail.push_back(arr[0]);

14     for (int i = 1; i < n; i++) {

15         if (arr[i] < tail[0]) tail[0] = arr[0];

16         else if (arr[i] > tail[tail.size()-1]) tail.push_back(arr[i]);

17         else {

18             int mid;

19             int left = 0;

20             int right = tail.size() - 1;

21             while (left < right) {

22                 mid = (left + right) / 2;

23                 if (tail[mid] < arr[i]) left = mid + 1;

24                 else right = mid - 1;

25             }

26             mid = (left + right) / 2;

27             tail[mid] = arr[i];

28             cout << "tail[" << mid << "] is arr[" << i << "] = " << arr[i] << endl;

29         }

30     }

31     return tail.size();

32 }

33 

34 int main() {

35     int arr[9] = {2, 5, 3, 7, 11, 8, 10, 13, 6};

36     cout << maxsum(arr, 9) << endl;

37     return 0;

38 }