//This is recurrssive function
//Note: Since we alredy did the padding, here both node1 and node2 will be of same length for sure
public NodeAdditionResult AddTwoLinkedListNodesFromTail(Node node1, Node node2)
{
//stop the recurrsion at this condition
if (node1 == null && node2 == null)
{
NodeAdditionResult emptynode = new NodeAdditionResult();
return(emptynode);
}
//we have to do the addition from right to left so call the recurrsion first
NodeAdditionResult runnerresult = new NodeAdditionResult();
//Both the node is of same size..but during recursion stop the recursion when the next is null
//so both node1 and node2 will be null at the same time
runnerresult = AddTwoLinkedListNodesFromTail(node1 != null ? node1.Next : null, node2 != null ? node2.Next : null);
int total = runnerresult.carry;
if (node1 != null)
{
total = total + node1.Data;
}
if (node2 != null)
{
total = total + node2.Data;
}
//if the total is 12 add 2 to the node and add 1 to the carry
//here resultnode will have the result of the right of the current node
//append the resultnode with the result of the current node...it will be current result --> right result
runnerresult.resultnode = NodeHelper.AddNodeToFirst(runnerresult.resultnode, total % 10);
runnerresult.carry = total >= 10 ? 1 : 0;
return(runnerresult);
}
public Node AddTwoLinkedListFromBackwards(KarthicLinkedList list1, KarthicLinkedList list2)
{
int length1 = NodeHelper.GetLength(list1);
int length2 = NodeHelper.GetLength(list2);
Node result = new Node();
Node node1 = new Node();
Node node2 = new Node();
if (length1 > length2)
{
//Add padding to the shortest list
node2 = NodeHelper.AddPadding(list2.headnode, (length1 - length2));
node1 = list1.headnode;
}
else
{
node1 = NodeHelper.AddPadding(list1.headnode, (length2 - length1));
node2 = list2.headnode;
}
//here the two nodes will be of same size
NodeAdditionResult resultnode = AddTwoLinkedListNodesFromTail(node1, node2);
//After adding two list, if there are any carry over add it on the top
if (resultnode.carry > 0)
{
Node node = NodeHelper.AddNodeToFirst(resultnode.resultnode, resultnode.carry);
return(node);
}
return(resultnode.resultnode);
}