Software Engineer

Factorial can be calculated using following recursive formula : 

n! = n * (n-1)!

n! = 1 if n = 0 or n = 1

Factorial can also be calculated iteratively as recursion can be costly for large numbers. 

Factorial(n)
{
	Initialize a variable res = 1
	for (i = 2 to i <= n) do :
	res = res* i
	return res
}

This can be done by iterative swapping using two pointers. The first pointer points to the beginning of the string, whereas the second pointer points to the end. Both pointers keep swapping their elements and go towards each other. Essentially, the algorithm simulates the rotation of a string with respect to its midpoint.
Time Complexity : O(n)

Initialization
malloc() allocates a memory block of given size (in bytes) and returns a pointer to the beginning of the block. malloc() doesn’t initialize the allocated memory. 
calloc() allocates the memory and also initializes every byte in the allocated memory to 0. If you try to read the value of the allocated memory without initializing it, you’ll get 0 as it has already been initialized to 0 by calloc().

Parameters
malloc() takes a single argument, which is the number of bytes to allocate.
Unlike malloc(), calloc() takes two arguments: 
1) Number of blocks to be allocated. 
2) Size of each block in bytes.

Return Value
After successful allocation in malloc() and calloc(), a pointer to the block of memory is returned otherwise NULL is returned which indicates failure.

Sometimes the programmer fails to initialize the pointer with a valid address, then this type of initialized pointer is known as a dangling pointer in C.Dangling pointer occurs at the time of the object destruction when the object is deleted or de-allocated from memory without modifying the value of the pointer

The direct approach to solve this problem is to run two for loops and for every subarray check if it is the maximum sum possible. 
Time complexity: O(N^2), Where N is the size of the array.
Space complexity: O(1)

The efficient approach is to use Kadane's algorithm. It calculates the maximum sum subarray ending at a particular index by using the maximum sum subarray ending at the previous position. 
Steps : 
Declare two variables : currSum which stores maximum sum ending here and maxSum which stores maximum sum so far.
Initialize currSum = 0 and maxSum = INT_MIN.
Now, traverse the array and add the value of the current element to currSum and check : 
1. If currSum > maxSum, update maxSum equals to currSum.
2. If currSum < 0, make currSum equal to zero.
Finally, print the value of maxSum.

Storage Classes are used to describe the features of a variable/function. These features basically include the scope, visibility and life-time which help us to trace the existence of a particular variable during the runtime of a program.

C language uses 4 storage classes, namely :
1. auto : This is the default storage class for all the variables declared inside a function or a block. Hence, the keyword auto is rarely used while writing programs in C language. Auto variables can be only accessed within the block/function they have been declared and not outside them (which defines their scope).
 

2. extern : Extern storage class simply tells us that the variable is defined elsewhere and not within the same block where it is used. Basically, the value is assigned to it in a different block and this can be overwritten/changed in a different block as well. So an extern variable is nothing but a global variable initialized with a legal value where it is declared in order to be used elsewhere. It can be accessed within any function/block.
 

3. static : This storage class is used to declare static variables which are popularly used while writing programs in C language. Static variables have a property of preserving their value even after they are out of their scope! Hence, static variables preserve the value of their last use in their scope
 

4. register : This storage class declares register variables which have the same functionality as that of the auto variables. The only difference is that the compiler tries to store these variables in the register of the microprocessor if a free register is available. This makes the use of register variables to be much faster than that of the variables stored in the memory during the runtime of the program.

A copy constructor is a member function that initializes an object using another object of the same class. A copy constructor has the following general function prototype: 
ClassName (const ClassName &old_obj);

In C++, a Copy Constructor may be called in the following cases : 
1. When an object of the class is returned by value. 
2. When an object of the class is passed (to a function) by value as an argument. 
3. When an object is constructed based on another object of the same class. 
4. When the compiler generates a temporary object.

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