LeetCode 26: Remove Duplicates from Sorted Array - Interview Prep Ep 45

LeetCode 26. Remove Duplicates from Sorted Array

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Clarification:
Confused why the returned value is an integer but your answer is an array?
Note that the input array is passed in by reference, which means modification to the input array will be known to the caller as well.

Internally you can think of this:
// nums is passed in by reference. (i.e., without making a copy)
int len = removeDuplicates(nums);
// any modification to nums in your function would be known by the caller.
// using the length returned by your function, it prints the first len elements.
for (int i = 0; i smaller than len; i++) {
print(nums[i]);
}

Solution explained:

1. We can apply the two pointer technique: one slow pointer pointing towards the one that's the last known distinct element, one fast pointer keeping moving towards the end of the array to scan for the next possible unique element.
2. Finally, we just need to return the slow pointer position plus one.

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[Yakuza]

It took me a while to realize this wasn't javaScript. It's crazy how similar Java's syntax is.

[akalrove]

This is such a beautiful logic. We use the slow/fast pointer a lot in linkedlist so this is very good for that also.

[kelvinnguyen]

Have my interview for Amazon soon, your channel is a blessing.

[prakashnavin]

very great explanation sir keep it up

[ramonsanchez]

This made a lot more sense than the other tutorials thanks so much

[sugandhm]

Beautiful explanation using two pointer technique to solve this problem. Keep posting more brother

[AmitSingh-xgtm]

Such a simple and beautiful explanation. Superlike👍🏻

[iEatCarKeys]

Not sure if I'll get a reply since this video is 2 years old but I have a question:
If you switch nums[++i] to nums[i++] OR nums[ i + 1] why wouldn't it work?

[sye]

thanks, great explanation as always, just one problem in the description, the problem link is pointing to the Pascal's Triangle lol

[fernandotanase]

How long did it take you to build an intuition to this. I've been trying to learn Algos. & Data Struc. for the longest but I'm still dirt at it.

[victoriakisel]

It doesn't work if first two numbers of an array are the same. It only works by adding if statement before the for loop:
int print(int arr[], int size) {
int j = 0, k = 1;
if (arr[0] == arr[k]) {
cout << arr[0] << " ";
}
for (int i = 1; i < size; i++)
{
if (arr[j] != arr[i]) {
arr[++j] = arr[i];
cout << arr[j] << " ";
}

}
return j+1;

[bhavyashah]

Hello Fisher, why did you return i + 1 and not just i ? can you let me know?

[abhiram]

its a great explanation but why don't we use the second pointer from the end of the array

[louischou]

why did you use ++i instead of i++ in line 6?

[nardizena]

Oh man, after fighting through the rubbish pile of Indian explanations made in android phones... I get you. Subscribed.

[diproy]

nice explanation but you could've used a sketchpad i.e. jamboard/miro/paint.