Developer Associate

You are present at point ‘A’ which is the top-left cell of an M X N matrix, your destination is point ‘B’, which is the bottom-right cell of the same matrix. Your task is to find the total number of unique paths from point ‘A’ to point ‘B’.In other words, you will be given the dimensions of the matrix as integers ‘M’ and ‘N’, your task is to find the total number of unique paths from the cell MATRIX[0][0] to MATRIX['M' - 1]['N' - 1].

To traverse in the matrix, you can either move Right or Down at each step. For example in a given point MATRIX[i] [j], you can move to either MATRIX[i + 1][j] or MATRIX[i][j + 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.

There is a room with a door (closed) and three light bulbs. Outside the room, there are three switches, connected to the bulbs. You may manipulate the switches as you wish, but once you open the door you can’t change them. Identify each switch with its bulb. All bulbs are in working condition.

Given an input string 'S' and a pattern 'P', implement a regular expression matching with the support of two special characters ‘.’ (dot) and ‘*’(asterisk) where

1. ‘.’ matches to any single character.
2. ‘*’ matches to zero or more of the preceding element.

If the input string 'S' matches the pattern 'P', then return true else, return false.

Note:

1. You have to match the entire string with the pattern given.

2. Both the strings, 'S' and 'P' contain only lower-case alphabets.

3. Only the pattern will contain additional characters ‘*’ and ‘.’ along with alphabets.

You are given an array of integers 'ARR' of length 'N' and an integer Target. Your task is to return all pairs of elements such that they add up to Target.

Note:

We cannot use the element at a given index twice.

Follow Up:

Try to do this problem in O(N) time complexity.