###### tags: `Kiditech`

# Task on big O notation: Chapter 1

### 1.3 Task on big o
What is the big O notation of the following function ?

1. Indicate constant time complexity in terms of Big-O notation
A. 
O(n)

B. 
O(1) //answer

C. 
O(logn)

D. 
O(n^2)



2. Indicate exponential time complexity in terms of big-O notation?
A. 
O(n)

B. 
O(n^2) //answer

C. 
O(2^n)

D. 
O(logn)



3. What is the big o for the following function ?

list = [2,6,3,8,4,13,4]
size = 7
def print_all_combinations(list,size)
    for x in range(0,size):
        for i in range(0, size):
            print(x * i)

A. 
O(n)

B. 
O(n^2) //answer

C. 
O(2^n)

D. 
O(logn)


4. What is the big o for the following function ?

def double(n)
    return (n*2) 

A. 
O(1) //answer

B. 
O(n^2) 

C. 
O(2^n)

D. 
O(logn)

5. What is the big o for the following al·go·rithm?

for i in range( 1 , 20 ):
        print(i)


A. 
O(n) //answer

B. 
O(1) 

C. 
O(logn)

D. 
O(n^2)

(task description):

Here is a function call printLast() which take in a list
as argument.

This function will loop through the whole list and print out the last number from the list.

The big o notation for this function right now is o(n) since the runtime is base on the size of the list.

this is a bad designed, try to make it perform big o(1).

def printLast(list):
    last_index = len(list)-1
    size = len(list)
    for i in range(0,size):
        if i == last_index:
            print(list[i])
            
list = [2,5,1,8,9]
printLast(list)

(hint):
the last_index represents the last index of the element , we can just retun it.

(answer):

def printLast(list):
    last_index = len(list)-1
    print( list[last_index] )