SDE - 1

You are given a string ‘S’. Your task is to return all distinct palindromic substrings of the given string in alphabetical order.

A string is said to be palindrome if the reverse of the string is the same as the string itself.

For Example:

Consider ‘S’ = ‘abba’, all the possible substrings are [ ‘a’, ‘ab’, ‘abb’, 'abba', 'b', ‘ba’, 'bb', ‘bba’ ] out of which [ ‘a’, ‘abba’, 'b’, 'bb'] are palindromic substrings.

You are given a map of an island. Your task is to find the perimeter of the island. The map is represented by a binary grid where ‘0’ represents water, and ‘1’ represents the land.

Note:

There is only one island and water surrounding it. There are no lakes, i.e., all the water is connected. Each edge of the land is 1 unit.

For example:

You are given map = [[0, 0, 0, 0, 0],
                     [0, 0, 1, 0, 0],
                     [0, 1, 1, 1, 0],
                     [0, 0, 1, 0, 0]]

You are given the map as:

Here, it can be clearly seen the perimeter of the island is 12. Hence the answer is 12.

Ninja lives in a beautiful city known as Byteland. A grand festive event is going to be organised in the city. To make place for the event, King has ordered Ninja to clear the nearby forest. The forest can be represented in the form of ‘N’*‘M’ grid ‘FOREST’, where each cell of ‘FOREST’ can have one of the possible values:

0 -> The cell is empty and Ninja can pass through it.
‘X’  -> The cell contains a tree with a height equal to ‘X’ where  ‘X’ > 0 and Ninja can pass through it.
-1 -> The cell can not be visited by Ninja.

Ninja is present at the top left corner of ‘FOREST’ i.e. at cell(0,0) and he has to cut down all the trees in ‘FOREST’. In one step ninja can move to any one of the four directions: East, West, North, South.

There is a rule that Ninja must cut off the trees in order from shortest to tallest and after cutting a tree, the value of the cell will become 0.

While standing on a cell with a tree, Ninja always has a choice to cut the tree or pass through the cell. It is guaranteed that no two cells will have the same height and there will always be at least one tree that need to be cut off.

Your task is to help Ninja to cut down all trees in ‘FOREST’ with minimum steps and return the number of steps.

If there is at least one tree that can not be cut off then return -1.

For example :

If ‘FOREST’ is :
[1,2,0]
[-1,5,-1]
[0,6,7]

We can see we need 4 steps to cut down all trees as shown below:

So, the output will be 4.