## HackerRank: Gemstones

### Problem

John has discovered various rocks. Each rock is composed of various elements, and each element is represented by a lower-case Latin letter from ‘a’ to ‘z’. An element can be present multiple times in a rock. An element is called a gem-element if it occurs at least once in each of the rocks.

Given the list of N rocks with their compositions, display the number of gem-elements that exist in those rocks.

Input Format

The first line consists of an integer, N, the number of rocks.
Each of the next N lines contains a rock’s composition. Each composition consists of lower-case letters of English alphabet.

Constraints
1N100
Each composition consists of only lower-case Latin letters (‘a’-‘z’).
1≤ length of each composition 100

Output Format

Print the number of gem-elements that are common in these rocks. If there are none, print 0.

Sample Input

3
abcdde
baccd
eeabg


Sample Output

2


Explanation

Only “a” and “b” are the two kinds of gem-elements, since these are the only characters that occur in every rock’s composition.

## HackerRank: The Love-Letter Mystery

### Problem

James found a love letter his friend Harry has written for his girlfriend. James is a prankster, so he decides to meddle with the letter. He changes all the words in the letter into palindromes.

To do this, he follows two rules:

1. He can reduce the value of a letter, e.g. he can change d to c, but he cannot change c to d.
2. In order to form a palindrome, if he has to repeatedly reduce the value of a letter, he can do it until the letter becomes a. Once a letter has been changed to a, it can no longer be changed.

Each reduction in the value of any letter is counted as a single operation. Find the minimum number of operations required to convert a given string into a palindrome.

Input Format

The first line contains an integer T, i.e., the number of test cases.
The next T lines will contain a string each. The strings do not contain any spaces.

Constraints
1T10
1 length of string 10^4
All characters are lower case English letters.

Output Format

A single line containing the number of minimum operations corresponding to each test case.

Sample Input

4
abc
abcba
abcd
cba


Sample Output

2
0
4
2


Explanation

1. For the first test case, abc -> abb -> aba.
2. For the second test case, abcba is already a palindromic string.
3. For the third test case, abcd -> abcc -> abcb -> abca = abca -> abba.
4. For the fourth test case, cba -> bba -> aba.

## HackerRank: Alternating Characters

### Problem

Shashank likes strings in which consecutive characters are different. For example, he likes ABABA, while he doesn’t like ABAA. Given a string containing characters A and B only, he wants to change it into a string he likes. To do this, he is allowed to delete the characters in the string.

Your task is to find the minimum number of required deletions.

Input Format

The first line contains an integer T, i.e. the number of test cases.
The next T lines contain a string each.

Output Format

For each test case, print the minimum number of deletions required.

Constraints

1T10
1≤ length of string 10^5

Sample Input

5
AAAA
BBBBB
ABABABAB
BABABA
AAABBB


Sample Output

3
4
0
0
4


Explanation

AAAA A, 3 deletions
BBBBB B, 4 deletions
ABABABAB ABABABAB, 0 deletions
BABABA BABABA, 0 deletions
AAABBB AB, 4 deletions because to convert it to AB we need to delete 2 A’s and 2 B’s

## 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.