CareerCup

This q haunted me for sometime as designing a BigInt class is tremendous effort.

for interview I would start with

string firstNum="11231234454567900707070978989678967896789";
string secondNum="11231234454567900707070978989678967896789";

Now write your own Adder (remember 3 rd grade mathematics)
Now write your own Subtract(again use same logic)

string Add(string n1,string n2)
string Sub(string n1,string n2)

Now you can easily write Multiply and Division routine.

By taking some more pain, you can extend it for decimal numbers.

There should exist a better and efficient method.
But this "MIGHT" save your day. :D

I think linked list is better than string or arrays.

struct Node {
byte digit;
Node next;
}

For adding and subtracting, you just need to add a new node in the list that keeps the sum.
For multiplying and division, I would create 2 new lists where I keep the temporary results and the final.

Can we have a use case for this?
Where can this be used?

linkd list solution is cool

I can see how the linked list solution would work if the least significant bit is at the head of the list for adding, subtracting and multiplying but how would the division work? What would the temporary list be?

class operation
{
public static void main(String[] args)
{
ArrayList<Integer> no1=new ArrayList<Integer>();
ArrayList<Integer> no2=new ArrayList<Integer>();
String n1="1231231231242342342342342342";
String n2="122342345657568678678562342342";
int c=0;
while(c<n1.length())
{
no1.add(Integer.parseInt(n1.substring(c,c)));
c++;
}
c=0;
while(c<n2.length())
{
no2.add(Integer.parseInt(n2.substring(c,c)));
c++;
}

add(no1,no2);
}
public static void add(ArrayList<Integer> no1, ArrayList<Integer> no2)
{int temp=0, c;
ArrayList<Integer> no3=new ArrayList<Integer>();
while(c<no1.length() && c<no2.length())
{
no3.add((no1.get(c)+no2.get(c)+temp)%10);
temp=(no1.get(c)+no2.get(c))/10;
}

if(c<no2.length())
while(c<no2.length())
{
no3.add((no2.get(c)+temp)%10);
temp=0;
}
if(c<no1.length())
while(c<no1.length())
{
no3.add((no1.get(c)+temp)%10);
temp=0;
}

}

class operation
{
public static void main(String[] args)
{
ArrayList<Integer> no1=new ArrayList<Integer>();
ArrayList<Integer> no2=new ArrayList<Integer>();
String n1="1231231231242342342342342342";
String n2="122342345657568678678562342342";
int c=0;
while(c<n1.length())
{
no1.add(Integer.parseInt(n1.substring(c,c)));
c++;
}
c=0;
while(c<n2.length())
{
no2.add(Integer.parseInt(n2.substring(c,c)));
c++;
}

add(no1,no2);
}
public static void add(ArrayList<Integer> no1, ArrayList<Integer> no2)
{int temp=0, c;
ArrayList<Integer> no3=new ArrayList<Integer>();
while(c<no1.length() && c<no2.length())
{
no3.add((no1.get(c)+no2.get(c)+temp)%10);
temp=(no1.get(c)+no2.get(c))/10;
}

if(c<no2.length())
while(c<no2.length())
{
no3.add((no2.get(c)+temp)%10);
temp=0;
}
if(c<no1.length())
while(c<no1.length())
{
no3.add((no1.get(c)+temp)%10);
temp=0;
}

}