LeetCode Single Number Solution Explained - Java

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#coding #programming #softwareengineering

[@phungtruong6698]

This is the first time i use XOR when coding. It's easy, thank you Nick

[@NicoleVardo]

Not stupid at all! I really like this explanation with xor Better than the hashmaps. Thank you

[@shalsteven]

hasmap need O(n) space, it is forbidden

[@jankidepala]

Its been 4 hours I am trying to figure out XOR...Thanks :)

[@harinijeyaraman8789]

Love your videos man ! Good and concise explanations !

[@fedest]

Here’s my explanation on why it works, regardless of the order of the numbers:
Keep in mind that for any bit A, you have A^0 == A, and A^1 != A, or said differently, xor’ing with a 1 “flips” its value, and xor’ing with a 0 leaves it unchanged.
Now consider each individual bit position in the int result. As you traverse the array, you’ll see ints having either a 0 or 1 in that position. The total number of 1s seen for that position, indicates how many times the bit at that position in result is flipped. Of course, for duplicate numbers, you’ll see the same bit twice, and flipping a bit twice (or any even number of times) is the same as leaving it unchanged.
Since result starts with all the bits as 0, in the end the value for the bit at each position will be 1 iff the total number of 1s at that position is odd, and that can only happen if the unique number in the array has a 1 at that bit position. Therefore, all bits in result will have the same value as the bits in the unique number, so they are the same number.

[@nihak309]

Explanations helps breaking down the cloud of confusions thanks to you! :)

[@Gideon_Judges6]

Keep in mind that this solution only works if you have even numbers of duplicates (e.g. pairs as in the problem statement). As soon as you have odd number of duplicates it fails. Note that XOR is the binary operator of the more general n-ary odd function.

[@treyquattro]

the problem description did say that, which is the give-away that XOR is the solution

[@shriyamsharma2082]

Exactly, because if we pass [4,4,1,4] as an array so the program fails!

[@uHnodnarB]

@@shriyamsharma2082 the question pretty explicitly says that all numbers that occur more than once occur twice. So yes, that is expected behavior.

[@ankuraagarwal]

Thanks you Nick! Great job.

[@olenaqwerty7895]

thanks for the video. you are the only person on youtube with so many leet code problem solutions

[@Mrfuckyounigabitch]

This is so simple! Thank you!

[@mashak3765]

thank you for your explanation - really helpful!

[@treyquattro]

nicely explained. Any number XOR'd with itself is zero. Any number XOR'd with zero is the number itself. It really helps to know binary representations of numbers, and also assembler-level programming (although not strictly necessary) :)

[@yergalemteferi9557]

You did a good explanation and it is very clear thanks

[@jeffery821217]

you can show with this: 0^2^2, basically xor twice it's back to 0

[@tanyongtyy7963]

This is smart. Thanks!

[@niiazbekmamasaliev9828]

XOR makes sense!. good job!

[@freesoul2677]

Thank you!

[@jay-cover120]

a good way to think of this is that there's only one distinct element in the list, every other pair of duplicate elements are going to be 0 if doing the XOR operation. so the whole for loop is basically reduced to just doing one XOR operation, which is 0 XOR that distinct element. And that is why the initial value set to 0.

[@vanraj8169]

But the process is not that way!!
You can do it by performing every element sequentially. That's why he said, concept behind this is bit tricky.

[@artsysoul1050]

really good explanation

[@apollossevere8602]

This was Dope!!

[@souravsaha933]

Very nice 👍🏻

[@jeezradz]

thanks for the explanation!! not stupid at all.

[@saketpanchori6480]

To understand XOR just convert numbers into base 2(0 and 1) then try you will get the unique number always

[@sukantadasgupta9325]

Thank you... not stupid at all

[@3thanGamer]

can somebody explain what the ^= operator does?

[@sol5179]

I don't know why first solution uses less memory...

[@shalsteven]

which solution?

[@rishabhjain4546]

Anything stupid enough to solve this question is not stupid at all !

[@SK-yb7bx]

Nor