update your solution
class Solution {
func addTwoNumbers(_ l1: ListNode?, _ l2: ListNode?) -> ListNode? {
let result = ListNode()
var resultTail = result
var carry: Int = 0
var out: Int = 0
var val1: Int = 0
var val2: Int = 0
var head1: ListNode? = l1
var head2: ListNode? = l2
while (l1 != nil || l2 != nil || carry != 0) {
val1 = head1 != nil ? head1!.val : 0
val2 = head2 != nil ? head2!.val : 0
out = (val1 + val2 + carry) % 10
carry = (val1 + val2 + carry) / 10
resultTail.next = ListNode(out)
resultTail = resultTail.next!
if let getHead1 = head1?.next {
head1 = getHead1
} else {
print("head1 next is nil")
break
}
if let getHead2 = head2?.next {
head2 = getHead2
} else {
print("head2 next is nil")
break
}
}
return result.next!
}
}
Just out of curiosity I've taken a look at what happens under the hood, and I've used [dtruss/strace][1] on each test.
C++
./a.out < in
Saw 6512403 lines in 8 seconds. Crunch speed: 814050
syscalls `sudo dtruss -c ./a.out < in`
CALL COUNT
__mac_syscall 1
<snip>
open 6
pread 8
mprotect 17
mmap 22
stat64 30
read_nocancel 25958
Python
./a.py < in
Read 6512402 lines in 1 seconds. LPS: 6512402
syscalls `sudo dtruss -c ./a.py < in`
CALL COUNT
__mac_syscall 1
<snip>
open 5
pread 8
mprotect 17
mmap 21
stat64 29
[1]: http://en.wikipedia.org/wiki/Strace
