//This solution is used when reversing the linked list is allowed.
public ListNode AddTwoNumbers(ListNode l1, ListNode l2)
{
ListNode reversedFirstNode = ReverseLinkedList(l1);
ListNode reversedSecondNode = ReverseLinkedList(l2);
//Display(reversedFirstNode);
//Display(reversedSecondNode);
int sum = 0, carry = 0;
ListNode resultNode = null, lastNode = null;
while (reversedFirstNode != null && reversedSecondNode != null)
{
//Console.WriteLine("First Node :- " + reversedFirstNode.val + " Second Node :- " + reversedSecondNode.val);
sum = reversedFirstNode.val + reversedSecondNode.val + carry;
carry = sum / 10;
sum %= 10;
//Console.WriteLine("Sum :- " + sum + " Carry :- " + carry);
if (resultNode == null)
{
resultNode = new ListNode(sum);
lastNode = resultNode;
}
else
{
lastNode.next = new ListNode(sum);
lastNode = lastNode.next;
}
reversedFirstNode = reversedFirstNode.next;
reversedSecondNode = reversedSecondNode.next;
//Display(resultNode);
}
while (reversedFirstNode != null)
{
sum = reversedFirstNode.val + carry;
carry = sum / 10;
sum %= 10;
if (resultNode == null)
{
resultNode = new ListNode(sum);
lastNode = resultNode;
}
else
{
lastNode.next = new ListNode(sum);
lastNode = lastNode.next;
}
reversedFirstNode = reversedFirstNode.next;
}
while (reversedSecondNode != null)
{
sum = reversedSecondNode.val + carry;
carry = sum / 10;
sum %= 10;
if (resultNode == null)
{
resultNode = new ListNode(sum);
lastNode = resultNode;
}
else
{
lastNode.next = new ListNode(sum);
lastNode = lastNode.next;
}
reversedSecondNode = reversedSecondNode.next;
}
if (carry > 0)
{
lastNode.next = new ListNode(carry);
lastNode = lastNode.next;
}
//Display(resultNode);
return ReverseLinkedList(resultNode);
}
//This solution is used when reversing the linked list is not allowed.
public ListNode AddTwoNumbersWithoutReversing(ListNode nodeA, ListNode nodeB)
{
Stack<int> firstNodeStack = new Stack<int>();
Stack<int> secondNodeStack = new Stack<int>();
PushLinkedListIntoStack(nodeA, firstNodeStack);
PushLinkedListIntoStack(nodeB, secondNodeStack);
int sum = 0, carry = 0;
ListNode resultNode = null, lastNode = null;
while (firstNodeStack.Count != 0 && secondNodeStack.Count != 0)
{
sum = firstNodeStack.Pop() + secondNodeStack.Pop() + carry;
carry = sum / 10;
sum %= 10;
//Console.WriteLine("Sum :- " + sum + " Carry :- " + carry);
if (resultNode == null)
{
resultNode = new ListNode(sum);
lastNode = resultNode;
}
else
{
lastNode.next = new ListNode(sum);
lastNode = lastNode.next;
}
//Display(resultNode);
}
while (firstNodeStack.Count != 0)
{
sum = firstNodeStack.Pop() + carry;
carry = sum / 10;
sum %= 10;
if (resultNode == null)
{
resultNode = new ListNode(sum);
lastNode = resultNode;
}
else
{
lastNode.next = new ListNode(sum);
lastNode = lastNode.next;
}
}
while (secondNodeStack.Count != 0)
{
sum = secondNodeStack.Pop() + carry;
carry = sum / 10;
sum %= 10;
if (resultNode == null)
{
resultNode = new ListNode(sum);
lastNode = resultNode;
}
else
{
lastNode.next = new ListNode(sum);
lastNode = lastNode.next;
}
}
if (carry > 0)
{
lastNode.next = new ListNode(carry);
lastNode = lastNode.next;
}
//Display(resultNode);
return ReverseLinkedList(resultNode);
}
