SDE - Intern

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. 

You are given an array 'A' of length 'N'. You can perform the operation defined below any number of times (Possibly 0).

Choose 'l', 'r' (1 <= 'l' <= 'r' <='N') and reverse the subarray from 'l' to 'r'.

After that, Return the maximum possible sum of the prefix of this array of length 'K'.

For Example:-

Let 'N' = 5, 'K' = 3, 'A' = [4, 2, 1, 2, 2].
We can reverse the subarray from index 3 to 4 (1-based indexing).
Array becomes [4, 2, 2, 1, 2].
Our answer is 8.

Design a data structure to implement ‘N’ stacks using a single array of size ‘S’. It should support the following operations:

push(X, M): Pushes an element X into the Mth stack. Returns true if the element is pushed into the stack, otherwise false.

pop(M): Pops the top element from Mth Stack. Returns -1 if the stack is empty, otherwise, returns the popped element.

Two types of queries denote these operations :

Type 1: for push(X, M) operation.
Type 2: for pop(M) operation.

Given an array with N elements, the task is to reverse all the array elements and print the reversed array.

You have been given a non-empty grid consisting of only 0s and 1s. You have to find the number of islands in the given grid.

An island is a group of 1s (representing land) connected horizontally, vertically or diagonally. You can assume that all four edges of the grid are surrounded by 0s (representing water).