Find Duplicate element in an array || 2 methods

This video shows 2 processes to find duplicate element in any type of array. First method is shown using SET data structure and second process by simply negating elements of an array.
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[CallMeKRSNA]

Not working sec code and also not clearly explained..

[jalsacentre]

ERROR IN 2ND APPROACH.
abs( A(i)) is always >=0.
So it should be A[ abs(a[i])].

[shouryasingh]

what if 0 is present in array, negative of 0 is zero

[SomnathDas-fgqc]

2nd approach not understood everytime it is checking absolute calue so each iteration if statement will work, can u explain it again with correction

[nadraibrahim]

1st method mein agr input mein hm ek hi element ko baar baar daal di en... To ue baar baar print krata rhega..
Ex- 1, 2, 2, 1, 1
Ouput will be- 2, 1, 1

[sakthim]

Tech dose I have a doubt in the second approach, you are checking the absolute value of each number, when you checking element at index 3, the value is -3, then abs(-3) is 3 and 3 is greater than 0 man then how it will move to else block and how it will print the duplicate number??? Are you crazy?? I did the code for this algorithm but it's not printing any result. If I wrong send the code or if you wrong then explain🙁

[askchaitanya]

The problem comes with an assumption that values inside the array will be in the range [0, size-1]. So the idea is as follows. Whenever we traverse an element with value i, we make the ith indexed element as negative. So whenever we come across a duplicate element with ths same i value and try to make the ith indexed element as negative, it is already negative. Hence we arrived at the duplicate element. The absolute check is for when a current element is already negated by another element in order to avoid IndexOutOfBoundException. Sounds good!!

[nithinbosej]

What is there is a 100 in the array input? Like - [100, 1, 3, 2, 3, 5]

[SunitaSharma-bipm]

Insertion and searching in set will take log(n) time, so the time complexity will be n*log(n).Am I right?

[haseen]

First method doesn't work if element is repeated more that 2 time, it gives duplicate output

[CallMeKRSNA]

Correct code link is given in description u can chk frm there.👍

[arkoprovo]

Awesome video 😊.
Plz give the 1st code also 🙏

[nagarajupandaga]

How negative elements greater than 0 not working

[RTX_valorant]

Asked in my interview no idea😭😭😭now understood

[sunnymaurya]

Even this approach is good because you are checking based on indexes values


if the array size is 4 and it contains value like arr[11, 15, 22, 15] then it won't work man

[akashmore]

This is very unprofessional. Second method not explained properly youtuber was in hurray

[faizanowaishvlogs]

you should remove this vedio its not correct