Merge pull request neetcode-gh#553 from adamMRamos/scala/2-add-two-nu…

…mbers

Scala/2-add-two-numbers

scala/2-Add-Two-Numbers.scala

@@ -0,0 +1,42 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode(_x: Int = 0, _next: ListNode = null) {
+ * var next: ListNode = _next
+ * var x: Int = _x
+ * }
+ */
+object Solution {
+ def addTwoNumbers(l1: ListNode, l2: ListNode): ListNode = {
+ def nonNull(l: ListNode): Boolean = l != null
+ def next(l: ListNode): ListNode = if (nonNull(l)) l.next else null
+ def getX(l: ListNode): Int = if (nonNull(l)) l.x else 0
+ def sumX(l1: ListNode, l2: ListNode, carry: Int): (ListNode, Int) = {
+ val sum = getX(l1) + getX(l2) + carry
+ new ListNode(sum % 10) -> sum / 10
+ }
+
+ var carry = 0
+ val (sum, newCarry) = sumX(l1, l2, carry)
+ carry = newCarry
+
+ var nextDigit = sum
+ var next1 = next(l1)
+ var next2 = next(l2)
+
+ while (nonNull(next1) || nonNull(next2)) {
+ val (sum, newCarry) = sumX(next1, next2, carry)
+
+ nextDigit.next = sum
+ nextDigit = nextDigit.next
+
+ carry = newCarry
+ next1 = next(next1)
+ next2 = next(next2)
+ }
+
+ if (carry > 0)
+ nextDigit.next = new ListNode(carry)
+
+ sum
+ }
+}