LeetCode Add Two Numbers Solution Explained - Java

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[ManishSingh-djyu]

Great.. one suggestion though. Please move your picture position to down left.

[reggiecook]

Some how this was the only video that could explain the solution to me. thanks

[shyamutty]

the numbers are bit confusing here because 243+564 = 807 and if you reverse the numbers 342+465 = 807

[NavedKhan-jeel]

Hey Nick, Thanks for the explanation. It would be a great help if you provide the solution of problem 445 i.e Add two numbers II.

[tiffanywong]

i get almost all of it, i can see how its added and carried over, i just dont understand which part revereses the linked node so that it can be added the way it is added

[laurawu]

thanks for sharing. very clear explanation. Im preparing for my interview, I like your video

[leetcodebaby]

I dont get it. When we never assigned any next Node to dummy_head. How did dummy_head still print the right answer?

[jennalefort]

Thank you! This was the first time I was able to understand the solution to this problem.

[tadashimatsumoto]

Really easy tutorial to follow, thanks a ton!

[HiBMlive]

hey. thanks for the video. Would be great if you could either decrease the sound of the keyboard clicks or use a better microphone.

[riyasvaliyadan]

Thank you brother for your explanation.

[Munchen]

Imo it’s more convenient (val_1 + val_2) % 10 further we can check if val_1 + val2 >= 10

[maherjabbar]

ListNode dummy_head = new ListNode(0);

what does the (0) mean, why we have it there?

[ff]

is that capital one's hack t-shirt ur wearing?

[nitinkallappa]

What if we have much larger numbers? Sum must be long type right

[coolilshat]

You could improve this further by doing it with O(1) space if you reuse nodes of the longer number

[ziakhan-tkrk]

Do you practice all problem beforehand and them present them here or is it you solve on the spot ??

[iamnoob]

Passes 1560/1563 test cases.


class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
StringBuilder s1 = new StringBuilder("");
StringBuilder s2 = new StringBuilder("");
while(l1!=null){
s1.append(l1.val);
l1 = l1.next;
}
while(l2!=null){
s2.append(l2.val);
l2 = l2.next;
}
String t1 = s1.reverse().toString();
String t2 = s2.reverse().toString();
long i1 = Long.parseLong(t1);
long i2 = Long.parseLong(t2);
long i3 = i1+i2;
if(i3==0){
return new ListNode(0);
}
ListNode dummy = new ListNode(-1);
ListNode head = dummy;
while(i3!=0){
int k = (int)(i3%10);
i3 = i3/10;
head.next = new ListNode(k);
head = head.next;
}
return dummy.next;


}
}

[tdizzleshizzle]

wat about the 0 in the list during initialization wouldnt that lead to a wrong answer?

[kimieti]

how is the carry not being brought over from the first time? wouldn’t it be .7?