exams activity selection

we have 2 options for giving a exam whether we can give the exam on ai-th day or b-ith day.
here we have to moove greedily. like sort the values in non-decreasing order of ai. because
we have to give the exam in such a way so that our ai-should be in increasing order.
and for a subject to choose we will be choosing bi only when if we choose bi and because of
that choosing, the corresponding ai which is going to be listed on the record shoul be arranged
in non decreasing manner other wise we will be choosing ai.
 given that ai > bi means as we have sorted ai so previous bi i.e. bi-1 will also be
less than current ai as we have sorted.

int ans = t[0][1]; // for the first subject we are choosing greedily the lowest day number

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

	int schedule = t[i][0];
	int attendable = t[i][1];
	// making the i-th schedule, which will be listed, in non decreasing order.
	if (ans <= attendable) ans = attendable;
	else ans = schedule;
}

input:
3
3 2
5 1
6 4
output:
6

initially list is empty. i.e. []
for the first subject we are choosing to give exam in 2nd day greedily. and list becomes [3].
for the second if we choose to give exam on 1st day then list will be [5, 3] which is not a non-decreasing
sequence to make this non decreasing we have to give second subject exam on day 5 and list will be [3, 5]
which is non decreasing. and now for the 3rd subject if we choose to give exam on 4-th day list will be
[3,6,5] which is again non decreasing because we have given the second subject's exam on day 5 so to make
the whole list increasing we have to give exam of 3rd subject on day 6 and list will become [3, 5, 6].