Doubt in csacademy problem

#1

I am not able to understand editorial for this problem - https://csacademy.com/contest/fii-code-2020-final-round-mirror/task/traveling-time/

Any other but understandable solution would also be fine.

Thanks.

#2

hello @yuvi2701 please share the link of the editorial as well .
i will try to explain editorial first and then i would try to explain any other approach .

#3

here - https://csacademy.com/contest/archive/task/traveling-time/solution/

#4

@yuvi2701 have you seen any code of this problem ?

#5

hey @yuvi2701 please see this code :


tell me if you dont understand anything .

#6

I read the code but its not clear. Can you please tell why do we sort by (t_i - l_i) ? Sorting by t_i is understandable. Sorting by l_i is understandable. But why by (t_i - l_i) ?

#7

HELLO @yuvi2701 please see this line in editorial :
We will sort the trains by t_i - li
​​ and in case of equality by li.
​​ . This way, we cannot take a train i after taking a train j>i because we would be behind it.

#8

Suppose
l1 = 1 , t1 = 4
l2 = 8 , t2 = 9

Then (t2 - l2) < (t1 - l1). But we can take train 2 after train 1.
I just don’t understand core idea behind sorting with (ti - li).

#9

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