3Sum | LeetCode 15 | C++, Java, Python

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July LeetCoding Challenge | Problem 8 | 3Sum | 8 July,
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[bittupandey]

I always look for your explanation it is crisp and clear !!

[mukultaneja]

2 pointer approach is awesome. But sir can we do it with DP...? I spent 3 hours in it....I even took 4D DP array but but didn't get correct solution. It was easily done with the help of (coin change) recursion.

[praveen]

Hi
Won' t the logic you explained for 2-SUM change the indices post sorting? In order to use the left-right logic, we need to sort the array. Once sorted, the indices will get updated. So the i and j will reflect indices of sorted array not the original array.
Can you please clarify?

[jlo]

Thanks a lot! helps me figur out how to code it.

[Mr.Starmaker]

Amazing !! Loved this Time order and code together thank you

[rishisharma]

Awesome video sir!!!
Keep posting them

[emanejaz]

Thankyou for the effort. You explained it really well.

[senthilkumar]

Thank you so much for a simpler solution!!!

[adarshmv]

Just one doubt: In python code - Line 17 - i had written 'if' instead of 'elif' and one tc was failing. What diff it will make?
because all 3 conditions are different right i.e summ == 0, summ < 0 and summ > 0 so anyway only either of these should execute. (btw we've to use summ not sum as var name - bcoz sum is keyword in python)

[kushaalrana]

Thank you well explained👍 and we'll coded too I didn't knew the use of this -> {} operator in vector but now I do. Thanks to you👌

[anishsuman]

Gajab search for one element in sorted array takes logn time

[crankyinmv]

Thanks, This is the strategy I used as well, though I couldn't do better than 43% on the time. Maybe because I did the 2sum part as a separate function and in JS.
Anyhoo, here's a possible optimization (right after line 9 in the C++ code):
if(nums[i] > 0) break;

ehilr

[naidusunny]

while(j < k && nums[j] == nums[j+1]) j++;
while(j < k && nums[k] == nums[k-1]) k--;
Can someone explain me what is the use these 2 while loops?

[anandmishra]

2 while condition we are checking for sum==0.... We could check these conditions for sum>0 and sum<0

[pratyushranjansahu]

Thanks for the explanation. Always i skip the problem..Now always i have to attain... :)

[TechWithKomal]

How could i reach u, either give yours Instagram handle or linkedin profile