I am getting TLE in this problem. I used lazy propagation with co-ordinate compression.

Link of the problem:- http://www.spoj.com/problems/POSTERS/

Code:- https://pastebin.com/cy0Zvx0Q

How do I apply co-ordinate compression here ?

If points (1,4), (2,6), (8,10), (3,4), (7,10). If I sort it and stor the indices in hashmap, then (1,2,3,4,6,7,8,10) will be compressed to (1,2,3,4,5,6,7,8).If I compress it this way then it fails for this test case.

6

1 3

4 6

6 7

8 1

1 2

3 4

I get answer as 4 because poster 3 at point (5,5) is not stored here as we have no index for 5.

I am newbie to this topic. Any help would be appreciated.