SDE - 1

Mike is a little boy who loves solving math problems. One day he was playing with his mom’s mobile. The mobile keypad contains 12 buttons { 10 digits(0-9) and 2 characters(‘*’ and ‘#’) }. Mike wants to know how many different numbers he can generate after pressing exactly the 'N' buttons on the keypad. Mike presses the buttons with the following rules:

1. He always presses the button which has a digit written on it, i.e., he never presses the ‘*’ and ‘#’ button.
2. Once he presses a button, the next button he presses should either be the same button or the button which is adjacent to the previous button.
3. In starting he can press any button except ‘*’ and ‘#’.

Mike is too little to solve this problem. Help Mike to solve this problem. As the answer can be large, so find the answer modulo 10^9 + 7.

You are given a string ('STR') of length 'N'. Find the longest palindromic substring. If there is more than one palindromic substring with the maximum length, return the one with the smaller start index.

Note:

A substring is a contiguous segment of a string.

For example : 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 "aba" starting index is less than "bab", so "aba" is the answer.

You are given an array/list ARR consisting of N integers. Your task is to find the maximum possible sum of a non-empty subarray(contagious) of this array.

Note: An array C is a subarray of array D if it can be obtained by deletion of several elements(possibly zero) from the beginning and the end of array D.

For e.g.- All the non-empty subarrays of array [1,2,3] are [1], [2], [3], [1,2], [2,3], [1,2,3].

You have been given a Binary Tree of distinct integers and two nodes ‘X’ and ‘Y’. You are supposed to return the LCA (Lowest Common Ancestor) of ‘X’ and ‘Y’.

The LCA of ‘X’ and ‘Y’ in the binary tree is the shared ancestor of ‘X’ and ‘Y’ that is located farthest from the root.

Note :

You may assume that given ‘X’ and ‘Y’ definitely exist in the given binary tree.

For example :

For the given binary tree

LCA of ‘X’ and ‘Y’ is highlighted in yellow colour.

You are given an 'N * N' matrix of integers where each row and each column is sorted in increasing order. You are given a target integer 'X'.

Find the position of 'X' in the matrix. If it exists then return the pair {i, j} where 'i' represents the row and 'j' represents the column of the array, otherwise return {-1,-1}

For example:

If the given matrix is:
[ [1, 2, 5],
  [3, 4, 9],
  [6, 7, 10]] 
We have to find the position of 4. We will return {1,1} since A[1][1] = 4.

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