Given an array, the task is to reverse the array without using subtract sign ‘-‘ anywhere in your code. It is not tough to reverse an array but the main thing is to not use ‘-‘ operator.
Asked in: Moonfrog Interview
Below are different approaches:
1- Store array elements into a vector in C++.
2- Then reverse the vector using predefined functions.
3- Then store reversed elements into the array back.
1- Store array elements into a stack.
2- As the stack follows Last In First Out, so we can store elements from
top of the stack into the array which will be itself in a reverse manner.
1- In this method, the idea is to use a negative sign but by storing it into a variable.
2- By using this statement x = (INT_MIN/INT_MAX), we get -1 in a variable x.
3- As INT_MIN and INT_MAX have same values just of opposite signs, so on dividing them it will give -1.
4- Then ‘x’ can be used in decrementing the index from last.
6 1 2 7 3 5
In this method 4, the idea is to use bitwise operator to implement subtraction i.e.
A – B = A + ~B + 1
so, i– can be written as i = i +~1 +1
6 1 2 7 3 5
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