#codingexercise

/***

Add 2 numbers represented as linked list and return the resulting sum as a linked list.

How are numbers represented as linked list?

Suppose we have 459, it is represented as:

4->5->9->null

So 4 is the head and 9 is the tail.

Say we are given 2 numbers like: 459 and 891, their sum is 1350. That will be represented as:

1->3->5->0.

Implement the function that takes head pointer of 2 numbers as linked list and

returns a head pointer to a new linked list, which is basically the sum of both the numbers.

***/

Node GetSum(Node root1, Node root2)

{

// read the value from root 1

int val1 = GetValue(root1);

// read the value from root 2

int val2 = GetValue(root2);

// write the value of root1 + root2

if ( val1 + val2 < val1 || val1 + val2 < val2) // overflow

   return NULL; // or raise exception

return WriteValue(val1 + val2);

}

Node WriteValue(int val)

{

  Node root = NULL;

  int v = val;

  int len = 0;

  while (v != 0 ) {

    len = len + 1;

    v  = v / 10;

  }

  v =  val;

  Node Prev = null;

  for ( i = 0; i < len ; i++)

  {

    var n = new Node();

    n.Data = (Math.floor(v / Power(10, len - i - 1))) % 10;

    n.Next = Null;

    if (Prev) {

        prev.next = n;

        prev = n;

    }

    else

        root = n;

       

  }

  return root;

}

int GetValue(Node root1)

{

Node cur = root1;

int val1 = 0;

int len = 0;

while(cur) 

{

  

   len = len + 1;

   cur = cur.Next;

}

// len = 2

cur = root1;

for ( i = 0; i < len; i++)

{

  val1 += cur.Data * Power(10, len - i - 1);

  cur = cur.Next;

}

// val1 = 29

}

NULL list2

list1 NULL

UnitValue List2

list1 UnitValue

ArbitraryValue List2

List1 ...

Overflow & Underflow