HackerRank Problem #1

Repeated String

riaevnt

2 min read

·

Sep 17, 2024

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Problem

There is a string, s, of lowercase English letters that is repeated infinitely many times. Given an integer, n, find and print the number of letter a's in the first n letters of the infinite string.

Example
s = ‘abcac’
n = 10

The substring we consider is abcacabcac, the first 10 characters of the infinite string. There are 4 occurrences of a in the substring.

Function Description

Complete the repeatedString function in the editor below.

repeatedString has the following parameter(s):

• s: a string to repeat
• n: the number of characters to consider

Returns

• int: the frequency of a in the substring

Input Format

The first line contains a single string, s.
The second line contains an integer, n.

Constraints

• 1≤ |s| ≤100
• 1≤n≤10¹²
• For 25% of the test cases, n≤10⁶ .

Sample Input

Sample Input 0

aba
10

Sample Output 0

7

Explanation 0
The first n=10 letters of the infinite string are abaabaabaa. Because there are 7a's, we return 7.

Sample Input 1

a
1000000000000

Sample Output 1

1000000000000

Explanation 1
Because all of the first n = 1000000000000 letters of the infinite string are a, we return 1000000000000.

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 'repeatedString' function below.
     *
     * The function is expected to return a LONG_INTEGER.
     * The function accepts following parameters:
     *  1. STRING s
     *  2. LONG_INTEGER n
     */
    public static long calculateAinString(String s, long size){
        long result=0;
        for(int i=0; i<size; i++){
            if(s.charAt(i) == 'a'){
                result = result+1;
            } 
        }
        return result;
    }

    public static long repeatedString(String s, long n) {
        // Write your code here
        int sSize = s.length();
        long aInTotal = 0;
        
        //a in a string
        long aInString = calculateAinString(s, sSize);
        
        if(n>sSize){
            long kelipatan = n/sSize;
            aInTotal =+ aInString*kelipatan;
            long sisa = n-(kelipatan*sSize);
            long aInSisa = calculateAinString(s, sisa);
            aInTotal = aInTotal + aInSisa;
        } else{
            aInTotal = calculateAinString(s, n);
        }
        
        System.out.println("aInTotal: "+aInTotal);
        
        return aInTotal;
    }

}

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 s = bufferedReader.readLine();

        long n = Long.parseLong(bufferedReader.readLine().trim());

        long result = Result.repeatedString(s, n);

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

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