namikaze:

fails some test cases, for example,
arr = [2,6,10,1,0];
correct answer should be [2,4,6,4,2], yours:

GREATIGBOMAN:
1. Two Sum
Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

GREATIGBOMAN:
2. Palindrome Number
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

Example 1:

Input: 121
Output: true

Example 2:

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

GREATIGBOMAN:
namikaze can u be posting like 1 question per day?

Sleekcode:
greatigboman Banned.

Remove Duplicates from Sorted Array
Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

Example 1:

Given nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.

It doesn't matter what you leave beyond the returned length.

Example 2:

Given nums = [0,0,1,1,1,2,2,3,3,4],

Your function should return length = 5, with the first five elements of nums being modified to 0, 1, 2, 3, and 4 respectively.

It doesn't matter what values are set beyond the returned length.

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.

In a nutshell.
Remove the duplicate in a given sorted array without creating any extra array then return the length after modifying the original given array.

GREATIGBOMAN:


checkout my solution:

https://www.jdoodle.com/ia/BZ8

Devdevdev:


Your solution is a brute Force O of n squared solution that has you iterating over every element in the array. What if you have 1 million numbers in the array? This will take hours to compute.

The faster solution would be something like this:

I'm using python here.

Create a function. I'll call it findTwoSum
say the array of numbers is defined as myNumbers
And our Target value is defined as target

def find_Two_Sum() {

Create an empty dictionary and give it a name,

myDict = {}

for index, number in enumerate(myNumbers):
difference = target - number
if difference in myDict:
return [myDict[difference], index]
return myDict[number] = index
}

Devdevdev:


Your solution is a brute Force O of n squared solution that has you iterating over every element in the array. What if you have 1 million numbers in the array? This will take hours to compute.

The faster solution would be something like this:

I'm using python here.

Create a function. I'll call it findTwoSum
say the array of numbers is defined as myNumbers
And our Target value is defined as target

def find_Two_Sum() {

Create an empty dictionary and give it a name,

myDict = {}

for index, number in enumerate(myNumbers):
difference = target - number
if difference in myDict:
return [myDict[difference], index]
return myDict[number] = index
}

GREATIGBOMAN:


Post it somewhere where u can share your answer

Devdevdev:


I tried to copy the link to my solution but I didn't find it. It is my first time using the site. So I took a screenshot of my solution. As you can see, mine compiled in 1.006 seconds, while yours compiled in 1.77 secs. This was just an array of length 4. If it was an array of 1 million numbers, it would literally take hours for yours to compile because you are iterating over the numbers linearly and comparing them one by one, whereas my solution will take seconds.

If you doubt me, try increasing the array length and compare both our solutions.

GREATIGBOMAN:


I didn't doubt you.

They're both correct.... Python is generally faster than JavaScript.

Not like yours will run exactly same time with array length of a million.

Sleekcode:
Letter Combinations of a Phone Number
Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent.

A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.




Example:

Input: "23"
Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].
Note:

Although the above answer is in lexicographical order, your answer could be in any order you want.

Difficulty= Medium

map = {
    '2':"abc",'3':"def",'4':"ghi",
    '5':"jkl", '6':"mno",'7':"pqrs",
    '8':"tuv",'9':"wxyz"
}
 
def letterCombinations(s, cur="", res=[]):
  if s == "":
    res.append(cur)
    return 
 
  n, s = s[0], s[1:]
  for adj in map[n]:
    letterCombinations(s, cur+adj, res)
    
  return res
  

s = "23"
print(letterCombinations(s))

Devdevdev:


This isn't about whether python is faster than Javascript. The crux of the matter is that my solution is faster than yours. It is not about the language but about the solution. You could apply a better solution in Javascript that would compile in a faster time, that is if you swallow your ego, sit down and think of how to do that.

If you present your solution in an interview you will fail that interview woefully.

Java is way faster than python but if I implemented your solution in java it will still be slower than the implementation of my solution in python.

DSA questions don't test correctness, they test speed, memory management, efficiency and scalability. For someone who spends a lot of time insulting people that "cannot code", I thought this is something you should know by now.

Devdevdev:


I tried to copy the link to my solution but I didn't find it. It is my first time using the site. So I took a screenshot of my solution. As you can see, mine compiled in 1.006 seconds, while yours compiled in 1.77 secs. This was just an array of length 4. If it was an array of 1 million numbers, it would literally take hours for yours to compile because you are iterating over the numbers linearly and comparing them one by one, whereas my solution will take seconds.

If you doubt me, try increasing the array length and compare both our solutions.

qtguru:


"Premature optimization is the root of evil", the difference in speed is not that much to worry about,

GREATIGBOMAN:


By your own logic if I was to provide a solution faster than yours that would render your current solution useless?

You should note that replying you is very stressful for me... You always sound like a loud entitled Karen or a 50 year old angry lady who's now trying to make something out of her failed life.

Devdevdev:


You still don't want to accept that your solution is slow and will give you a FAIL in an interview.

Ordinary this simple algorithm question and you can't provide an efficient solution. How will you now solve harder questions efficiently?

Set awon Nairaland troll. Maybe if you invest all the time you use in trolling and insulting people into practicing DSA questions, you'll get better. You are still at level zero. Providing brute force solution to ordinary Two Sum question.

It's clear that all my hard work is paying off. The more knowledgeable I become the more I realize just how much of a quack people like you are. Continue trolling Nairaland from morning till night while I invest my time improving my coding skills.

Devdevdev:


The difference in speed will be much if the length of the array increases exponentially.

Devdevdev:


You still don't want to accept that your solution is slow and will give you a FAIL in an interview.

Ordinary this simple algorithm question and you can't provide an efficient solution. How will you now solve harder questions efficiently?

Set awon Nairaland troll. Maybe if you invest all the time you use in trolling and insulting people into practicing DSA questions, you'll get better. You are still at level zero. Providing brute force solution to ordinary Two Sum question.

It's clear that all my hard work is paying off. The more knowledgeable I become the more I realize just how much of a quack people like you are. Continue trolling Nairaland from morning till night while I invest my time improving my coding skills.