So I just found out that my solution which is almost same as this one gets TLE on test case 8 while latter got AC.
I can't figure-out why this happened?
Problem link -> C.Save More Mice
It turns out that Arrays.sort() in java uses Quicksort which has worst time complexity of O(n^2) and Collections.sort() uses that has time complexity of O(nlogn).
refer to this article for more information.