## HackerRank: Modified Kaprekar Numbers

### Problem:

A modified Kaprekar number is a positive whole number n with d digits, such that when we split its square into two pieces – a right hand piece r with d digits and a left hand piece l that contains the remaining d or d1 digits, the sum of the pieces is equal to the original number (i.e. l + r = n).

Note: r may have leading zeros.

Here’s an explanation from Wikipedia about the ORIGINAL Kaprekar Number (spot the difference!): In mathematics, a Kaprekar number for a given base is a non-negative integer, the representation of whose square in that base can be split into two parts that add up to the original number again. For instance, 45 is a Kaprekar number, because 45² = 2025 and 20+25 = 45.

You are given the two positive integers p and q, where p is lower than q. Write a program to determine how many Kaprekar numbers are there in the range between p and q (both inclusive) and display them all.

Input Format

There will be two lines of input: p, lowest value q, highest value

Constraints:
0<p<q<100000

Output Format

Output each Kaprekar number in the given range, space-separated on a single line. If no Kaprekar numbers exist in the given range, print INVALID RANGE.

Sample Input

1
100


Sample Output

1 9 45 55 99

Explanation

1, 9, 45, 55, and 99 are the Kaprekar Numbers in the given range.

## HackerRank: Paint The Tiles

Problem

Nikita has a line of N tiles indexed from 0 to N−1. She wants to paint them to match a color configuration, C, which is comprised of 2 colors: Red(R) and Blue(B)

In one stroke, Nikita can paint 1 or more adjacent tiles a single color. After she finishes painting, each tile(i) should be painted color C(i).

It should be noted that it is not allowed to apply more than 1 stroke on a tile.

Given the required color configuration, find and print the minimum number of strokes required for Nikita to paint all N tiles.

Note: In a line of tiles, 2 tiles with the indices i and j are considered adjacent only if |ji|=1.

Input Format

The first line contains a single integer, N, denoting the number of tiles to be painted.
The second line contains a string, C, denoting the desired color configuration.

For each character C(i) in C:

• If C(i)=“R”, it means the ith tile must be painted red.
• If C(i)=“B”, it means the ith tile must be painted blue.

Constraints

• 1N1000
• C(i){“R”, “B”}

Output Format

Print the minimum number of strokes required to paint all tiles in the desired color configuration.

Sample Input 0

5
RRRRR


Sample Output 0

1


Sample Input 1

5
RRBRR


Sample Output 1

3


Sample Input 2

5
BRBRB


Sample Output 2

5


Explanation

Sample Case 0:

Nikita will paint all 5 consecutive tiles red in a single stroke:

Sample Case 1:

Nikita will need 3 strokes to paint all 5 tiles:

Solution:

## HackerRank: The Time in Words

### Problem

Given the time in numerals we may convert it into words, as shown below:

5:00 → five o’ clock
5:01 → one minute past five
5:10 → ten minutes past five
5:30 → half past five
5:40 → twenty minutes to six
5:45 → quarter to six
5:47 → thirteen minutes to six
5:28 → twenty eight minutes past five

Write a program which prints the time in words for the input given in the format mentioned above.

Input Format

There will be two lines of input:
H, representing the hours
M, representing the minutes

Constraints
1H<12
0M<60

Output Format

Display the time in words.

Sample Input

5
47


Sample Output

thirteen minutes to six

## HackerRank: Taum and B’day

### Problem

Taum is planning to celebrate the birthday of his friend, Diksha. There are two types of gifts that Diksha wants from Taum: one is black and the other is white. To make her happy, Taum has to buy B number of black gifts and W number of white gifts.

• The cost of each black gift is X units.
• The cost of every white gift is Y units.
• The cost of converting each black gift into white gift or vice versa is Z units.

Help Taum by deducing the minimum amount he needs to spend on Diksha’s gifts.

Input Format

The first line will contain an integer T which will be the number of test cases.
There will be T pairs of lines. The first line of each test case will contain the values of integers B and W. Another line of each test case will contain the values of integers X, Y, and Z.

Constraints
1T10
0X,Y,Z,B,W10^9

Output Format

T lines, each containing an integer: the minimum amount of units Taum needs to spend on gifts.

Sample Input

5
10 10
1 1 1
5 9
2 3 4
3 6
9 1 1
7 7
4 2 1
3 3
1 9 2


Sample Output

20
37
12
35
12


Explanation

• Sample Case #01: There is no benefit to converting the white gifts into black or the black gifts into white, so Taum will have to buy each gift for 1 unit. So cost of buying all gifts will be: 101+101=20.
• Sample Case #02: Again, we can’t decrease the cost of black or white gifts by converting colors. We will buy gifts at their original price. So cost of buying all gifts will be: 52+93=10+27=37.
• Sample Case #03: We will buy white gifts at their original price, 1. For black gifts, we will first buy white one and color them to black, so that their cost will be reduced to 1+1=2. So cost of buying all gifts will be: 32+61=12.
• Sample Case #04: Similarly, we will buy white gifts at their original price, 2. For black gifts, we will first buy white one and color them to black, so that their cost will be reduced to 2+1=3. So cost of buying all gifts will be: 73+72=35.
• Sample Case #05: We will buy black gifts at their original price, 1. For white gifts, we will first black gifts worth 1 unit and color them to white with another 2 units, so cost for white gifts is reduced to 3 units. So cost of buying all gifts will be: 31+33=3+9=12.

Solution

## HackerRank: Extra Long Factorials

### Problem

You are given an integer N. Print the factorial of this number.

N!=N×(N1)×(N2)××3×2×1

Input
Input consists of a single integer N, where 1N100.

Output
Print the factorial of N.

Example
For an input of 25, you would print 15511210043330985984000000

Note: Factorials of N>20 can’t be stored even in a 64bit long long variable. Big integers must be used for such calculations. Languages like Java, Python, Ruby etc. can handle big integers, but we need to write additional code in C/C++ to handle huge values.

We recommend solving this challenge using BigIntegers.

## HackerRank: ACM ICPC Team

### Problem

You are given a list of N people who are attending ACM-ICPC World Finals. Each of them are either well versed in a topic or they are not. Find out the maximum number of topics a 2-person team can know. And also find out how many teams can know that maximum number of topics.

Note Suppose a, b, and c are three different people, then (a,b) and (b,c) are counted as two different teams.

Input Format

The first line contains two integers, N and M, separated by a single space, where N represents the number of people, and M represents the number of topics. N lines follow.
Each line contains a binary string of length M. If the ith line’s jth character is 11, then the ith person knows the jth topic; otherwise, he doesn’t know the topic.

Constraints
2N500
1M500

Output Format

On the first line, print the maximum number of topics a 2-person team can know.
On the second line, print the number of 2-person teams that can know the maximum number of topics.

Sample Input

4 5
10101
11100
11010
00101


Sample Output

5
2


Explanation

(1, 3) and (3, 4) know all the 5 topics. So the maximal topics a 2-person team knows is 5, and only 2 teams can achieve this.

## HackerRank: Lisa’s Workbook

### Problem

Lisa just got a new math workbook. A workbook contains exercise problems, grouped into chapters.

• There are n chapters in Lisa’s workbook, numbered from 1 to n.
• The i-th chapter has ti problems, numbered from 1 to ti.
• Each page can hold up to k problems. There are no empty pages or unnecessary spaces, so only the last page of a chapter may contain fewer than k problems.
• Each new chapter starts on a new page, so a page will never contain problems from more than one chapter.
• The page number indexing starts at 1.

Lisa believes a problem to be special if its index (within a chapter) is the same as the page number where it’s located. Given the details for Lisa’s workbook, can you count its number of special problems?

Note: See the diagram in the Explanation section for more details.

Input Format

The first line contains two integers n and k — the number of chapters and the maximum number of problems per page respectively.
The second line contains n integers t1,t2,,tn where ti denotes the number of problems in the ii-th chapter.

Constraints

• 1n,k,ti100

Output Format

Print the number of special problems in Lisa’s workbook.

Sample Input

5 3
4 2 6 1 10


Sample Output

4


Explanation

The diagram below depicts Lisa’s workbook with n=chapters and a maximum of k=3 problems per page. Special problems are outlined in red, and page numbers are in yellow squares.

There are 4 special problems and thus we print the number 4 on a new line.

## HackerRank: Manasa and Stones

### Problem

Manasa is out on a hike with friends. She finds a trail of stones with numbers on them. She starts following the trail and notices that two consecutive stones have a difference of either a or b. Legend has it that there is a treasure trove at the end of the trail and if Manasa can guess the value of the last stone, the treasure would be hers. Given that the number on the first stone was 0, find all the possible values for the number on the last stone.

Note: The numbers on the stones are in increasing order.

Input Format
The first line contains an integer T, i.e. the number of test cases. T test cases follow; each has 3 lines. The first line contains nn (the number of stones). The second line contains a, and the third line contains b.

Output Format
Space-separated list of numbers which are the possible values of the last stone in increasing order.

Constraints
1T10
1n,a,b10^3

Sample Input

2
3
1
2
4
10
100


Sample Output

2 3 4
30 120 210 300


Explanation

All possible series for the first test case are given below:

1. 0,1,2
2. 0,1,3
3. 0,2,3
4. 0,2,4

Hence the answer 2 3 4.

Series with different number of final steps for second test case are the following:

1. 0, 10, 20, 30
2. 0, 10, 20, 120
3. 0, 10, 110, 120
4. 0, 10, 110, 210
5. 0, 100, 110, 120
6. 0, 100, 110, 210
7. 0, 100, 200, 210
8. 0, 100, 200, 300

Hence the answer 30 120 210 300.

### Solution

Original solution source

## HackerRank: CodeWhiz.java March 2016: Serve the Students

### Problem

In this problem, there are 22 types of events: ENTER (a student enters the queue) or SERVED.

A unique token is assigned to any student entering the queue. The queue serves the students based on the following criteria:

1. The student having the highest Cumulative Grade Point Average (CGPA) is served first.
2. Any students having the same CGPA will be served by name in ascending case-sensitive alphabetical order.
3. Any students having the same CGPA and name will be served in ascending token order.

Given a sequence of nn events, print the names of students who are yet to be served(based on above criteria). If the queue is empty, print EMPTY.

Input Format

The first line of input contains an integer, nn, denoting the total number of events. Each of the nn subsequent lines will be of the following two forms:

1. ENTER name CGPA token – The student to be inserted into the priority queue.
2. SERVED – The highest priority student in the queue was served.

Constraints

• 2n1000
• 0CGPA4.00 where CGPAR
• 1token(i)10where each token(i) is a unique integer.
• 2|name|30

Output Format

Print the names (based on the criteria) of the students who are not served at all after executing all n events; if every student in the queue was served, then print EMPTY.

Sample Input

12
ENTER John 3.75 50
ENTER Mark 3.8 24
ENTER Shafaet 3.7 35
SERVED
SERVED
ENTER Samiha 3.85 36
SERVED
ENTER Ashley 3.9 42
ENTER Maria 3.6 46
ENTER Anik 3.95 49
ENTER Dan 3.95 50
SERVED


Sample Output

Dan
Ashley
Shafaet
Maria


Explanation

Let’s call our queue Q.

n0: We add John to the empty queue.
Q0={(John, 3.75, 50)}

n1: We add Mark to the queue; Q1={(John, 3.75, 50),(Mark, 3.8, 24)

n2: We add Shafaet to the queue; Q2={(John, 3.75, 50),(Mark, 3.8, 24),(Shafaet, 3.7, 35)}

n3: Mark is served as he has the highest CGPA; P3={(John, 3.75, 50),(Shafaet, 3.7, 35)}

n4: John is served next as he has the highest CGPA; P4={(Shafaet, 3.7, 35)}

n5: We add Samiha to the queue; Q2={(Shafaet, 3.7, 35),(Samiha, 3.85, 36)}

n6: Samiha is served as she has the highest CGPA; P6={(Shafaet, 3.7, 35)}

n7 through n10, the next four students are added giving us:  Q10={(Shafaet, 3.7, 35),(Ashley, 3.9, 42),(Maria, 3.6, 46),(Anik, 3.95, 49),(Dan, 3.95, 50)}

n11: Anik is served because though both Anil and Dan have the highest CGPA but Anik comes first when sorted in alphabetic order; P11={(Dan, 3.95, 50),(Ashley, 3.9, 42),(Shafaet, 3.7, 35),(Maria, 3.6, 46)}

As all events are completed, we print names of each remaining students on a new line.

## HackerRank: CodeWhiz.java March 2016: Maximum and Minimum

### Problem

The locked code in your editor passes array A (of size N) and index i to the print method, whose try block attempts to print element A[i]; if i is Out-of-Range, an Array Index Out Of Bounds Exception is thrown.

Complete the code in your editor so that it prints the maximum and minimum elements in array A—regardless of whether or not an exception is thrown.

Input Format

The first line contains an integer, N, the number of elements in A.
The second line contains N space-separated integers describing A.
The third line contains an index, i, to be accessed.

Note: Input from stdin handled by the locked code in the editor.

Constraints

• 1N100
• 1000Aj1000 where 1jN

Output Format

The try block will print the value accessed at A[i]; if an Exception is thrown, it will be printed by the locked code in your editor.
You must print the respective maximum and minimum values in array A as a single pair of space-separated integers on a new line—regardless of whether an exception is thrown.

Note: Observe that your max/min values may print on either the first or second line, depending on whether or not an Exception was thrown!

Sample Input 0

12
-12 0 1 -899 23 45 96 10 75 23 0 33
100


Sample Output 0

96 -899
java.lang.ArrayIndexOutOfBoundsException


Sample Input 1

10
4 908 -05 445 -208 325 -2 -718 863 400
9


Sample Output 1

400
908 -718


Explanation

Sample 0:
N=12, i=100, maximum(A)=96, and minimum(A)=899
A‘s indices range from 0 to 11, so attempting to access index 100 throws an Exception. The maximum and minimum values in the array are printed on a new line as a pair of space-separated integers. The program’s control flow then returns to main where the the Exception is caught and printed on a new line.

Sample 1:
N=10, i=9, maximum(A)=908, and minimum(A)=718
A‘s indices range from 0 to 9, so an attempt to access index 9 will be successful and the value at A[9] (i.e.: 400) is printed on a new line. The program’s control flow then proceeds to print the maximum and minimum values in A as a pair of space-separated integers on a new line.