Senior Software Engineer

You and your friend found a string ‘S’ of length ‘N’. You love to rearrange the strings, So you decided to rearrange this string too. But this time, your friend puts a constraint on rearranging. He gave you ‘M’ pairs of integers, each pair denoting two indices of the string ‘S’. He also gave you an operation. In one operation, you can select a pair of indices from the given ‘M’ pairs and swap the character present at those indices in the string.

Your task is to rearrange the strings following the given constraints and find the lexicographically smallest string that you can obtain by doing the operations any number of times (might be 0 as well).

You are given a non-decreasing array 'arr' consisting of 'n' integers and an integer 'x'. You need to find the first and last position of 'x' in the array.

Note:

1. The array follows 0-based indexing, so you need to return 0-based indices.
2. If 'x' is not present in the array, return {-1 -1}.
3. If 'x' is only present once in the array, the first and last position of its occurrence will be the same.

Example:

Input:  arr = [1, 2, 4, 4, 5],  x = 4

Output: 2 3

Explanation: The given array’s 0-based indexing is as follows:
 1      2     4     4     5
 ↓      ↓     ↓     ↓     ↓
 0      1     2     3     4

So, the first occurrence of 4 is at index 2, and the last occurrence of 4 is at index 3.

You are given roots of two binary trees, ‘ROOT1’ and ‘ROOT2’. You need to merge the two trees into a new binary tree. The merge rule is that if the two nodes overlap, then the sum of the two nodes values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of the new tree. Your task is to return the merged tree i.e. head of the new tree.

Note:

The merging process must start from the root nodes of both trees.

For example,

‘ROOT1’ = [1, 2, -1, -1, 3, -1, -1]  ‘ROOT2’ = [3, -1, -1].
The final tree would look like : [3, 2, -1, -1, 3, -1, -1], and the output will be printed in a pre-order way: 4 2 3.

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

Your task is to reverse the original string word by word.

There can be multiple spaces between two words and there can be leading or trailing spaces but in the output reversed string you need to put a single space between two words, and your reversed string should not contain leading or trailing spaces.

Example :

If the given input string is "Welcome to Coding Ninjas", then you should return "Ninjas Coding to Welcome" as the reversed string has only a single space between two words and there is no leading or trailing space.

DB schema of a ticket booking system along with APIs endpoints and handling concurrency. Further asked to normalize the database.