HackerRank: [Algo] Matrix Rotation

Problem

You are given a 2-D matrix, a, of dimension M x N and a positive integer R. You have to rotate the matrix R times and print the resultant matrix. Rotation should be in anti-clockwise direction.

Rotation of a 4 x 5 matrix is represented by the following figure. Note that in one rotation, you have to shift elements by one step only (refer sample tests for more clarity).

matrix-rotation

It is guaranteed that the minimum of M and N will be even.

Input Format
First line contains three space separated integers, M, N and R, where M is the number of rows, N is number of columns in matrix, and R is the number of times the matrix has to be rotated.
Then M lines follow, where each line contains N space separated positive integers. These M lines represent the matrix.

Output Format
Print the rotated matrix.

Constraints
2 <= M, N <= 300
1 <= R <= 109
min(M, N) % 2 == 0
1 <= aij <= 108, where i[1..M] & j[1..N]

Sample Input #00

4 4 1
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16

Sample Output #00

2 3 4 8
1 7 11 12
5 6 10 16
9 13 14 15

Sample Input #01

4 4 2
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16

Sample Output #01

3 4 8 12
2 11 10 16
1 7 6 15
5 9 13 14

Sample Input #02

5 4 7
1 2 3 4
7 8 9 10
13 14 15 16
19 20 21 22
25 26 27 28

Sample Output #02

28 27 26 25
22 9 15 19
16 8 21 13
10 14 20 7
4 3 2 1

Sample Input #03

2 2 3
1 1
1 1

Sample Output #03

1 1
1 1

Explanation
Sample Case #00: Here is an illustration of what happens when the matrix is rotated once.

 1  2  3  4      2  3  4  8
 5  6  7  8      1  7 11 12
 9 10 11 12  ->  5  6 10 16
13 14 15 16      9 13 14 15

Sample Case #01: Here is what happens when to the matrix after two rotations.

 1  2  3  4      2  3  4  8      3  4  8 12
 5  6  7  8      1  7 11 12      2 11 10 16
 9 10 11 12  ->  5  6 10 16  ->  1  7  6 15
13 14 15 16      9 13 14 15      5  9 13 14

Sample Case #02: Following are the intermediate states.

1  2  3  4      2  3  4 10    3  4 10 16    4 10 16 22
7  8  9 10      1  9 15 16    2 15 21 22    3 21 20 28
13 14 15 16 ->  7  8 21 22 -> 1  9 20 28 -> 2 15 14 27 ->
19 20 21 22    13 14 20 28    7  8 14 27    1  9  8 26
25 26 27 28    19 25 26 27    13 19 25 26   7 13 19 25



10 16 22 28    16 22 28 27    22 28 27 26    28 27 26 25
 4 20 14 27    10 14  8 26    16  8  9 25    22  9 15 19
 3 21  8 26 ->  4 20  9 25 -> 10 14 15 19 -> 16  8 21 13
 2 15  9 25     3 21 15 19     4 20 21 13    10 14 20  7
 1  7 13 19     2  1  7 13     3  2  1  7     4  3  2  1

Sample Case #03: As all elements are same, any rotation will reflect the same matrix.

Solution

HackerRank: Cut the sticks

Problem

You are given N sticks, where the length of each stick is a positive integer. A cut operation is performed on the sticks such that all of them are reduced by the length of the smallest stick.

Suppose we have six sticks of the following lengths:
5 4 4 2 2 8

Then, in one cut operation we make a cut of length 2 from each of the six sticks. For the next cut operation four sticks are left (of non-zero length), whose lengths are the following:
3 2 2 6

The above step is repeated until no sticks are left.

Given the length of N sticks, print the number of sticks that are left before each subsequent cut operations.

Note: For each cut operation, you have to recalcuate the length of smallest sticks (excluding zero-length sticks).

Input Format
The first line contains a single integer N.
The next line contains N integers: a0, a1,…aN-1 separated by space, where ai represents the length of ith stick.

Output Format
For each operation, print the number of sticks that are cut, on separate lines.

Constraints
1 ≤ N ≤ 1000
1 ≤ ai ≤ 1000

Sample Input #00

6
5 4 4 2 2 8

Sample Output #00

6
4
2
1

Sample Input #01

8
1 2 3 4 3 3 2 1

Sample Output #01

8
6
4
1

Explanation

Sample Case #00 :

sticks-length        length-of-cut   sticks-cut
5 4 4 2 2 8             2               6
3 2 2 _ _ 6             2               4
1 _ _ _ _ 4             1               2
_ _ _ _ _ 3             3               1
_ _ _ _ _ _           DONE            DONE

Sample Case #01

sticks-length         length-of-cut   sticks-cut
1 2 3 4 3 3 2 1         1               8
_ 1 2 3 2 2 1 _         1               6
_ _ 1 2 1 1 _ _         1               4
_ _ _ 1 _ _ _ _         1               1
_ _ _ _ _ _ _ _       DONE            DONE

Solution

 

HackerRank: Service Lane

Problem

Calvin is driving his favorite vehicle on the 101 freeway. He notices that the check engine light of his vehicle is on, and he wants to service it immediately to avoid any risks. Luckily, a service lane runs parallel to the highway. The length of the service lane is N units. The service lane consists of N segments of equal length and different width.

Calvin can enter to and exit from any segment. Let’s call the entry segment as index i and the exit segment as index j. Assume that the exit segment lies after the entry segment (ij) and 0i0≤i. Calvin has to pass through all segments from index i to index j (both inclusive).

Paradise Highway

Calvin has three types of vehicles – bike, car, and truck – represented by 1, 2 and 3, respectively. These numbers also denote the width of the vehicle.

You are given an array width of length N, where width[krepresents the width of the kth segment of the service lane. It is guaranteed that while servicing he can pass through at most 1000 segments, including the entry and exit segments.

  • If width[k]=1, only the bike can pass through the kth segment.
  • If width[k]=2, the bike and the car can pass through the kth segment.
  • If width[k]=3, all three vehicles can pass through the kth segment.

Given the entry and exit point of Calvin’s vehicle in the service lane, output the type of the largest vehicle which can pass through the service lane (including the entry and exit segments).

Input Format

The first line of input contains two integers, N and T, where N denotes the length of the freeway and T the number of test cases. The next line has N space-separated integers which represent the width array.

T test cases follow. Each test case contains two integers, i and j, where i is the index of the segment through which Calvin enters the service lane and j is the index of the lane segment through which he exits.

Constraints
2N100000
1T1000
0i<j<N
2ji+1min(N,1000)
1width[k]3,where 0k<N

Output Format

For each test case, print the number that represents the largest vehicle type that can pass through the service lane.

Note: Calvin has to pass through all segments from index i to index j (both inclusive).

Sample Input

8 5
2 3 1 2 3 2 3 3
0 3
4 6
6 7
3 5
0 7

Sample Output

1
2
3
2
1

Explanation

Below is the representation of the lane:

   |HIGHWAY|Lane|    ->    Width

0: |       |--|            2
1: |       |---|           3
2: |       |-|             1
3: |       |--|            2
4: |       |---|           3
5: |       |--|            2
6: |       |---|           3
7: |       |---|           3
  1. (0, 3): Because width[2] = 1, only the bike can pass through it.
  2. (4, 6): Here the largest allowed vehicle which can pass through the 5th segment is the car and for the 4th and 6th segment it’s the truck. Hence the largest vehicle allowed in these segments is a car.
  3. (6, 7): In this example, the vehicle enters at the 6th segment and exits at the 7th segment. Both segments allow even trucks to pass through them. Hence the answer is 3.
  4. (3, 5): width[3] = width[5] = 2. While the 4th segment allows the truck, the 3rd and 5thallow up to a car. So 2 will be the answer here.
  5. (0, 7): The bike is the only vehicle which can pass through the 2nd segment, which limits the strength of the whole lane to 1.

Solution

 

HackerRank: BotClean Partially Observable

Problem Statement

The game Bot Clean took place in a fully observable environment, i.e., the state of every cell was visible to the bot at all times. Let us consider a variation of it where the environment is partially observable. The bot has the same actuators and sensors. But the sensors visibility is confined to its 8 adjacent cells.

Input Format
The first line contains two space separated integers which indicate the current position of the bot. The board is indexed using Matrix Convention

5 lines follow, representing the grid. Each cell in the grid is represented by any of the following 4 characters:
‘b’ (ascii value 98) indicates the bot’s current position,
‘d’ (ascii value 100) indicates a dirty cell,
‘-‘ (ascii value 45) indicates a clean cell in the grid, and
‘o’ (ascii value 111) indicates the cell that is currently not visible.

Output Format
Output is the action that is taken by the bot in the current step. It can either be any of the movements in 4 directions or the action of cleaning the cell in which it is currently located. Hence the output formats are LEFT, RIGHT, UP, DOWN or CLEAN.

Sample Input

0 0
b-ooo
-dooo
ooooo
ooooo
ooooo

Sample Output

RIGHT

Task
Complete the function next_move that takes in 3 parameters: posr and posc denote the co-ordinates of the bot’s current position, and board denotes the board state, and print the bot’s next move.

Scoring
The goal is to clean all the dirty cells in as few moves as possible. Your score is (200 – #bot moves)/25. All bots in this challenge will be given the same input. CLEAN is also considered a move.

Education Links

Solution:

Solution tester posted alongside the program for users to test their input as well.

 

HackerRank: Sherlock and Squares

Problem Statement

Watson gives two integers (and B) to Sherlock and asks if he can count the number of square integers between and (both inclusive).

Note: A square integer is an integer which is the square of any integer. For example, 1, 4, 9, and 16 are some of the square integers as they are squares of 1, 2, 3, and 4, respectively.

Input Format
The first line contains T, the number of test cases. test cases follow, each in a new line.
Each test case contains two space-separated integers denoting and B.

Output Format
For each test case, print the required answer in a new line.

Constraints
1T100
1AB10^9

Sample Input

2
3 9
17 24

Sample output

2
0

Explanation
Test Case #00: In range [3,9], 4 and 9 are the two square numbers.
Test Case #01: In range [17,24], there are no square numbers.

Solution:

 

HackerRank: Continuous Sequence Sum Test

Question:

Given a sequence of positive integers A and an integer T, return whether there is a continuous sequence of A that sums up to exactly T
Example

[23, 5, 4, 7, 2, 11], 20. Return True because 7 + 2 + 11 = 20
[1, 3, 5, 23, 2], 8. Return True because 3 + 5 = 8
[1, 3, 5, 23, 2], 7 Return False because no sequence in this array adds up to 7


Solution

HackerRank: BotClean

Problem Statement

The goal of Artificial Intelligence is to create a rational agent (Artificial Intelligence 1.1.4). An agent gets input from the environment through sensors and acts on the environment with actuators. In this challenge, you will program a simple bot to perform the correct actions based on environmental input.

Meet the bot MarkZoid. It’s a cleaning bot whose sensor is a head mounted camera and whose actuators are the wheels beneath it. It’s used to clean the floor.

The bot here is positioned at the top left corner of a 5*5 grid. Your task is to move the bot to clean all the dirty cells.

Input Format

The first line contains two space separated integers which indicate the current position of the bot.
The board is indexed using Matrix Convention
5 lines follow representing the grid. Each cell in the grid is represented by any of the following 3 characters: ‘b’ (ascii value 98) indicates the bot’s current position, ‘d’ (ascii value 100) indicates a dirty cell and ‘-‘ (ascii value 45) indicates a clean cell in the grid.

Note If the bot is on a dirty cell, the cell will still have ‘d’ on it.

Output Format

The output is the action that is taken by the bot in the current step, and it can be either one of the movements in 4 directions or cleaning up the cell in which it is currently located. The valid output strings are LEFT, RIGHT, UP and DOWN or CLEAN. If the bot ever reaches a dirty cell, output CLEAN to clean the dirty cell. Repeat this process until all the cells on the grid are cleaned.

Sample Input #00

0 0
b---d
-d--d
--dd-
--d--
----d

Sample Output #00

RIGHT

Resultant state

-b--d
-d--d
--dd-
--d--
----d

Sample Input #01

0 1
-b--d
-d--d
--dd-
--d--
----d

Sample Output #01

DOWN

Resultant state

----d
-d--d
--dd-
--d--
----d

Task

Complete the function next_move that takes in 3 parameters posr, posc being the co-ordinates of the bot’s current position and board which indicates the board state to print the bot’s next move.

The codechecker will keep calling the function next_move till the game is over or you make an invalid move.

Scoring

Your score is (200 – number of moves the bot makes)/40. CLEAN is considered a move as well.

Once you submit, your bot will be played on four grids with three of the grid configurations unknown to you. The final score will be the sum of the scores obtained in each of the four grids.

Education Links

Solution

HackerRank: Remove Duplicate Elements from a Linked list

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3..

Solution

HackerRank: Same Tree problem

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Return 0 / 1 ( 0 for false, 1 for true ) for this problem

Example :

Input :

    1        1
/ \     / \
2   3   2 3

Output :
1 or True

Array Rotation: bug detection

The following code is supposed to rotate the array A by B positions.

So, for example,

A : [1 2 3 4 5 6]
B : 1

The output :

[2 3 4 5 6 1]

However, there is a small bug in the problem. Fix the bug and submit the problem.