public static ListNodeLc2 AddTwoNumbers(ListNodeLc2 list1, ListNodeLc2 list2)
{
//1. Initialize current node to dummy head of the returning list
ListNodeLc2 dummyHead = new ListNodeLc2(0);
var curr = dummyHead;
//2. Initialize carry to 0.
int carry = 0;
//4. Loop through lists list1 and list2 until you reach both ends.
while (list1 != null || list2 != null)
{
// Set x to node list1's value. If list1 has reached the end of list1, set to 0.
int x = list1?.Value ?? 0;
// Set y to node list2's value. If list2 has reached the end of list2, set to 0.
int y = list2?.Value ?? 0;
// Set sum = x + y + carrysum = x + y + carrysum = x + y + carry.
int sum = x + y + carry;
// Update carry = sum / 10.
carry = sum / 10;
// Create a new node with the digit value of(sum mod 10)
curr.Next = new ListNodeLc2(sum % 10);
// and set it to current node's next, then advance current node to next.
curr = curr.Next;
// Advance both list1 and list2.
list1 = list1?.Next;
list2 = list2?.Next;
}
//5. Check if carry=1,
// if so append a new node with digit to the returning list
if (carry > 0)
{
curr.Next = new ListNodeLc2(carry);
}
// return dummyhead.next;
return(dummyHead.Next);
}
public ListNodeLc2(int value, ListNodeLc2 next = null)
{
this.Value = value;
this.Next = next;
}