SDE - Intern

Consider all numbers from 1 to ‘N’, your task is to find the sum of gcd of all pairs (i, j) such that 1 <= i < j <= N.

For example for N = 3, all pairs are { (1, 2), (1, 3), (2, 3) }.

Note :

Gcd of two numbers (X, Y) is defined as the largest integer that divides both ‘X’ and ‘Y’. 

You are given two strings 'S' and 'T' of lengths 'N' and 'M' respectively. Find the "Edit Distance" between the strings.

Edit Distance of two strings is the minimum number of steps required to make one string equal to the other. In order to do so, you can perform the following three operations:

1. Delete a character
2. Replace a character with another one
3. Insert a character

Note:

Strings don't contain spaces in between.

You are given an array 'arr' of length 'n'. Find the index(0-based) of a peak element in the array. If there are multiple peak numbers, return the index of any peak number.

Peak element is defined as that element that is greater than both of its neighbors. If 'arr[i]' is the peak element, 'arr[i - 1]' < 'arr[i]' and 'arr[i + 1]' < 'arr[i]'.

Assume 'arr[-1]' and 'arr[n]' as negative infinity.

Note:

1.  There are no 2 adjacent elements having same value (as mentioned in the constraints).
2.  Do not print anything, just return the index of the peak element (0 - indexed).
3. 'True'/'False' will be printed depending on whether your answer is correct or not.

Example:

Input: 'arr' = [1, 8, 1, 5, 3]

Output: 3

Explanation: There are two possible answers. Both 8 and 5 are peak elements, so the correct answers are their positions, 1 and 3.

Given a string STR of length N. The task is to return the count of minimum characters to be added at front to make the string a palindrome.

For example, for the given string “deed”, the string is already a palindrome, thus, minimum characters needed are 0.

Similarly, for the given string “aabaaca”, the minimum characters needed are 2 i.e. ‘a’ and ‘c’ which makes the string “acaabaaca” palindrome.

You are given an array ‘Arr’ consisting of ‘N’ distinct integers and a positive integer ‘K’. Find out Kth smallest and Kth largest element of the array. It is guaranteed that K is not greater than the size of the array.

Example:

Let ‘N’ = 4,  ‘Arr’ be [1, 2, 5, 4] and ‘K’ = 3.  
then the elements of this array in ascending order is [1, 2, 4, 5].  Clearly, the 3rd smallest and largest element of this array is 4 and 2 respectively.

You are given a string 'str' of length 'N'.

Your task is to return the longest palindromic substring. If there are multiple strings, return any.

A substring is a contiguous segment of a string.

For example :

str = "ababc"

The longest palindromic substring of "ababc" is "aba", since "aba" is a palindrome and it is the longest substring of length 3 which is a palindrome. 

There is another palindromic substring of length 3 is "bab". Since starting index of "aba" is less than "bab", so "aba" is the answer.