Doubts in answer of q2 and q8

#1

Q2. Choose the correct output and time complexity for the following code :

list< int > myList = { 2, 6, 12, 13, 15, 18, 20};
cout << binary_search(myList.begin(), myList.end(), 20) ;

why is the answer : time for linear traversal?

Q8.
Why the output is 132
begin()+3 will be the 3rd element or 4th element?

#2

@pradhumangupta99
In question 2
we are given list and list stl is very similar to the link list i.e we need to to traverse list from start to reach a particluar index.

if i represent recurrence relation for binary search on list then it will be something as ->

T(n)=T(n/2) + O(n) // O(n) because to reach to mid element we need to traverse half of the list which is equivalent to O(n) work.

On solving this recurrence relation we get O(n) time complexity

#3

@pradhumangupta99
In question 8, begin()+3 should point to 4th element

#4

in Q8 if begin()+3 represents 4th element then why is the answer to it 138? does last element is considered in max_element?

#5

can please post the full question.