HackerRank Lisa's Workbook Problem Solution

In this post, we will solve HackerRank Lisa’s Workbook Problem Solution.

Lisa just got a new math workbook. A workbook contains exercise problems, grouped into chapters. Lisa believes a problem to be special if its index (within a chapter) is the same as the page number where it’s located. The format of Lisa’s book is as follows:

There are n chapters in Lisa’s workbook, numbered from 1 to n.
The ¿th chapter has arr[i] problems, numbered from 1 to arr[i].
Each page can hold up to k problems. Only a chapter’s last page of exercises 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.
Given the details for Lisa’s workbook, can you count its number of special problems?

Example
arr = [4,2]
k = 3
Lisa’s workbook contains arr[1] = 4 problems for chapter 1, and arr[2] = 2 problems for chapter 2. Each page can hold k = 3 problems.
The first page will hold 3 problems for chapter 1. Problem 1 is on page 1, so it is special. Page 2 contains only Chapter 1, Problem 4, so no special problem is on page 2. Chapter 2 problems start on page 3 and there are 2 problems. Since there is no problem 3 on page 3, there is no special problem on that page either. There is 1 special problem in her workbook.
Note: See the diagram in the Explanation section for more details.

Function Description

Complete the workbook function in the editor below.

workbook has the following parameter(s):

int n: the number of chapters
int k: the maximum number of problems per page
int arr[n]: the number of problems in each chapter

Returns
– int: the number of special problems in the workbook

Input Format
The first line contains two integers n and k, the number of chapters and the maximum
number of problems per page.
The second line contains n space-separated integers arr[i] where arr[i] denotes the number of problems in the ¿th chapter.

Sample Input

STDIN       Function
-----       --------
5 3         n = 5, k = 3
4 2 6 1 10  arr = [4, 2, 6, 1, 10]

Sample Output

Explanation

The diagram below depicts Lisa’s workbook with n = 5 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 Lisa's Workbook Problem Solution — HackerRank Lisa’s Workbook Problem Solution

Lisa’s Workbook C Solution

#include <stdio.h>
#include <math.h>
int main()
{
    //printf("dfgh");
    int n, k, i, u, j, i_p, l_p, ttl_p, m_n, count;
    double m;
    scanf("%d %d", &n, &k);
    int pr[n];
    for(i=0; i<n; i++){
        scanf("%d", &pr[i]);
    }
    count = 0;
    l_p = 0;
    for(i=0; i<n; i++){
        m = (pr[i] * 1.00)/k;
        ttl_p = ceil(m);
        i_p = l_p + 1;
        l_p = i_p + ttl_p - 1;
        m_n = 0;
        for(j=i_p; j<=l_p; j++){
            for(u=0; u<k; u++){
                m_n++;
                if(j==m_n) count++;
                if(m_n==pr[i]) break;
            }
        }
    }
    printf("%d\n", count);
    return 0;
}

Lisa’s Workbook C++ Solution

#include<iostream>
#include<algorithm>
#include<vector>
#include<map>
#include<string>
#include<sstream>
#include<cmath>
#include<math.h>

using namespace std;

int main()
{
	int n, k, t;
	int p = 1;
	int r = 0;
	cin >> n >> k;
	for (int i = 1; i <= n; i++) 
	{
		cin >> t;
		for (int x = 1; x <= t; x++) 
		{
			if (p == x) 
				r++;
			if (x % k == 0) 
				p++;
		}
		if (t % k != 0) 
			p++;
	}
	cout << r << endl;
	return 0;
}

Lisa’s Workbook C Sharp Solution

using System;
using System.Collections.Generic;
using System.IO;
class Solution
{
    static void Main(String[] args)
    {
        int[] n = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
        int currentPage = 1;
        int numSpecial = 0;

        int[] data = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
        for (int i = 0; i < n[0]; i++)
        {
            int question = 1;

            while (question <= data[i])
            {
                if (question == currentPage)
                {
                    numSpecial++;
                }
                if (question % n[1] == 0 && question != data[i])
                    currentPage++;
                question++;
            }
            currentPage++;
        }
        Console.WriteLine(numSpecial);
    }
}

Lisa’s Workbook Java Solution

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

    /*
     * Complete the 'workbook' function below.
     *
     * The function is expected to return an INTEGER.
     * The function accepts following parameters:
     *  1. INTEGER n
     *  2. INTEGER k
     *  3. INTEGER_ARRAY arr
     */

    public static int workbook(int n, int k, List<Integer> arr) {
        int page = 1;
        int numSpecials = 0;

        for (int i = 0; i < n; ++i) {
            int numProblems = arr.get(i);
            int problem = 1;

            while (numProblems > 0) {
                int pageProblems = numProblems;
                pageProblems -= k;

                if (pageProblems > 0) {
                    pageProblems = k;
                } else {
                    pageProblems += k;
                }

                while (pageProblems > 0) {
                    if (page == problem) {
                        ++numSpecials;
                    }

                    ++problem;
                    --pageProblems;
                }

                numProblems -= k;
                ++page;
            }
        }

        return numSpecials;
    }

}

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");

        int n = Integer.parseInt(firstMultipleInput[0]);

        int k = Integer.parseInt(firstMultipleInput[1]);

        List<Integer> arr = Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
            .map(Integer::parseInt)
            .collect(toList());

        int result = Result.workbook(n, k, arr);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedReader.close();
        bufferedWriter.close();
    }
}

Lisa’s Workbook Javascript Solution

function processData(input) {
    //Enter your code here
    input = input.split('\n');
    var chapters = parseInt(input[0].split(' ')[0], 10);
    var perPage = parseInt(input[0].split(' ')[1], 10);
    var perChapter = input[1].split(' ');
    for(var i=0; i<chapters; i++) perChapter[i] = parseInt(perChapter[i], 10);
    
    var result = 0;
    var page = 1;
    for(var i=1; i<=chapters; i++) {
        for(var j=1; j<=perChapter[i-1]; j++) {
            if(j>1 && ((j-1) % perPage === 0)) page++;
            if(j===page) result++;
        }
        page++;
    }
    
    console.log(result);
} 

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});

Lisa’s Workbook Python Solution

from math import ceil

def get_split(x, k):
    r = []
    for i in range(ceil(x/k)):
        r.append(tuple(range(i*k+1, min((i+1)*k, x)+1)))
    return r

n, k = [int(x) for x in input().split()]
t = [int(x) for x in input().split()]

p = [ceil(x/k) for x in t]
r = [i for s in [get_split(x, k) for x in t] for i in s]
s = 0
for i in range(sum(p)):
    if ((i+1) in r[i]):
        s += 1
print(s)