Associate Software Engineer

Ninja is sitting in an examination hall. He is encountered with a problem statement, "Find ‘X’ to the power ‘N’ (i.e. ‘X’ ^ ‘N’). Where ‘X’ and ‘N’ are two integers."

Ninja was not prepared for this question at all, as this question was unexpected in the exam.

He is asking for your help to solve this problem. Help Ninja to find the answer to the problem.

Note :

For this question, you can assume that 0 raised to the power of 0 is 1.

An expression is called the postfix expression if the operator appears in the expression after the operands.

Example :

Infix expression: A + B  *  C - D 

Postfix expression:  A B + C D - *

Given a postfix expression, the task is to evaluate the expression. The answer could be very large, output your answer modulo (10^9+7). Also, use modular division when required.

Note:

1. Operators will only include the basic arithmetic operators like '*', '/', '+', and '-'.

2. The operand can contain multiple digits. 

3. The operators and operands will have space as a separator between them.

4. There won’t be any brackets in the postfix expression.

You are given an array 'A' of size 'N' and an integer 'K'.

The 'Pulse' of a subarray of 'A' is defined as the product of the number of even elements and the number of odd elements in that subarray.

Return the minimum possible length of a subarray having 'Pulse' greater than or equal to 'K'. If there does not exist any subarray having 'Pulse' greater than or equal to 'K', then return -1.

Note : Assume 0-based indexing.

A subarray is any contiguous part of an array.

For example:

Let 'N' = 5, 'K' = 4, 'A' = [2, 2, 2, 1, 1].
There exist only two subarrays, 'A[0…4]' and 'A[1…4]' having 'Pulse' greater than or equal to 'K'. 
'Pulse' of 'A[0…4]' is 6 and the length is 5.
'Pulse' of 'A[1…4]' is 4 and the length is 4.
 Since we have to minimize the length, therefore 4 will be our answer.