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List of questions which were asked during the online test 

1. Number of Unique Characters

Problem Statement:
You are required to implement the following function:
NumberUniqueCharacter(str)

The function accepts a string ‘str’ as its argument. You are required to calculate the number of unique characters in string ‘str’ and return the same.

Note:
If ‘str’=NULL, return -1

Assumptions:

• length of ‘str’ <=100000 characters
• ‘str’ contains only lower case alphabets.

Example:

Input
str: abcdabc
Output:
4
Explanation:
The string ‘str’ is “abcdabc”, and unique characters in string ‘str’ are {‘a’,’b’,’c’,’d’}, count of them is 4, hence 4 is returned.

Sample Input
str: efeefhjg
Sample Output
5

Solution:

Method 1

def NumberUniqueCharacter(str):
    count=0
    temp=""
    if str=="":
        return -1
    for i in str:
        if i not in temp:
            temp+=i
            count+=1
    return count
str="abcdabc"
print(NumberUniqueCharacter(str))
        

Method 2

def NumberUniqueCharacter(str):
    if str=="":
        return -1
    str=set(str)
    return len(str)
str="abcdabc"
print(NumberUniqueCharacter(str))

2. Maximum Index Product

Problem Statement
Implement the following function:
MaxIndexProduct(arr,n)

The function accepts an integer array ‘arr’ of size n. Implement the function to find and return maximum index product. For every index ‘j’, index product =Left(j) x Right(j). Left(j)=an index ‘k’ which is closest to index ‘j’ ,such that k<j and arr[k] > arr[j], if no such index ‘k’ exist then Left(j) = 0. Right(j) = an index ‘l’ which is closest to index ‘j’, such that l > j and srr[l] > arr[j], if no such index ‘I’ exists then Right(j) = 0.

Assumption:
Element at index 0 is the smallest.
Note:

• Return -1 if the array is empty(or None in the case of Python).
• Indexing starts from 0.

Example:
Input
arr: -3 4 3 6 4 5 -2
Output
15
Explanation:
Index Product:

• Index product of index 0 = 0 x 1 = 0
• Index product of index 1 = 0 x 3 = 0
• Index product of index 2 = 1 x 3 = 3
• Index product of index 3 = 0 x 0 = 0
• Index product of index 4 = 3 x 5 = 15
• Index product of index 5 = 3 x 0 = 0
• Index product of index 6 = 5 x 0 = 0
  The maximum index product is 15. Thus, the output is 15.

Sample Input
arr: 1 5 4 3 5 2
Sample Output
8

Solution

def maxIndexProduct(arr,n):
    product=0
    if n==0:
        return -1
    for j in range(1,n-1):
        left=0
        right=0
        for k in range(j-1,-1,-1):
            if arr[k]>arr[j]:
                left=k
                break
        for l in range(j+1,n):
            if arr[l]>arr[j]:
                right=l
                break
        if (left*right>product):
            product=left*right
    return product
ls=[int(x) for x in input().split()]
n=len(ls)
print(maxIndexProduct(ls,n)) 

Amazon Software Development Engineering Hiring Coding Question & Answer!