Q: you are give list of struct blocker;
struct {
int id;
int start;
int end;
};
and D as range of days for 1 to D;
you need to return list of days between 1 to D on which every one is free.

ex : {[1,2,3],[2,5,6]} and D = 6 , first is id, second is start last is end;

your ans = {1,4} cause both person are available on day 1 and 4;

there was one follow up for this return all days where person >= k are avialable.