SDE - Intern

 One Sentence (string) is given. find out the words, that has length even and greater than equal to 4 (e.g. 4,6,8.. etc.) and separate them with space.
e.g. Given String : “abcd abc abcde abcdef”
Output: “ab cd abc abcde abc def”
I allocated a new string dynamically, and used two for loops to copy one string to another, adding a space at the middle of the word where word length was >=4 and even. O(n^2) time complexity.

Check if binary conversion of given number is palindrome or not. Ex: 6 (0110) is palindrome.
I used a recursive function for binary conversion and then check for palindrome using a loop. Refrain from using inbuilt functions as they wanna check your logic. O(n) time complexity.

Then he made it complex by saying that if there are numbers from 0 to k in an array of size n then how will you sort them in O(n), I told him the count sort, he agreed with it and then asked me to quickly write down the code, I wrote it down, there was a silly mistake which he pointed out and said that it’s good and then moved on to next problem. He saw my code for fourth largest in an array, I did it using heap and time for creating heap is O(nlogn) then he checked the code which was perfectly fine. He then gave me a hint and asked me to do it in O(n) using something from quicksort