Hackerrank - Two Characters

Hackerrank – Problem Statement

A description of the problem can be found on Hackerrank.

Solution

I started with finding all unique characters.
Then I created all possible combinations of pairs.

I deleted other characters except the pair.
I found if the examined pair contains alternating characters in deleted strings
If yes I count the length of the string.

The result is the maximum of string lengths.

I created solution in:

Scala
Java
Javascript

All solutions are also available on my GitHub profile.

Scala

import scala.io.Source

object Solution extends App {
    val lines = Source.stdin.getLines().toList
    val s = lines.tail.head
    val characters = s.distinct
    val strings = (for {
        i <- 0 until characters.length - 1
        j <- i + 1 until characters.length
    } yield {
        val c1 = characters(i)
        val c2 = characters(j)
        val subset = s.replaceAll("[^" + c1 + "" + c2 + "]", "")
        subset
    }).filter(isAlternating)

    val maxLength = if(strings.isEmpty) 0 else strings.maxBy(_.length).length

    println(maxLength)

    def isAlternating(s: String): Boolean = s.sliding(2).forall(ss => ss(0) != ss(1))
}

import scala.io.Source

object Solution extends App {

val lines = Source.stdin.getLines().toList

val s = lines.tail.head

val characters = s.distinct

val strings = (for {

i <- 0 until characters.length - 1

j <- i + 1 until characters.length

} yield {

val c1 = characters(i)

val c2 = characters(j)

val subset = s.replaceAll("[^" + c1 + "" + c2 + "]", "")

subset

}).filter(isAlternating)

val maxLength = if(strings.isEmpty) 0 else strings.maxBy(_.length).length

println(maxLength)

def isAlternating(s: String): Boolean = s.sliding(2).forall(ss => ss(0) != ss(1))

}

Java

import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int len = in.nextInt();
        String s = in.next();

        Set<Character> distinct = new HashSet<>();
        for (int i = 0; i < len; i++) {
            distinct.add(s.charAt(i));
        }

        List<Character> distinctList = new ArrayList<>(distinct);

        int max = 0;
        for(int i = 0; i < distinct.size() - 1; i++) {
            for(int j = i + 1; j < distinct.size() ; j++) {
                char c1 = distinctList.get(i);
                char c2 = distinctList.get(j);
                String subset = s.replaceAll("[^" + c1 + "" + c2 + "]", "");
                if(isAlternating(subset)) {
                    int l = subset.length();
                    max = l > max ? l : max;
                }
            }
        }

        System.out.println(max);
    }

    private static boolean isAlternating(String s) {
        for(int i = 0; i < s.length() - 1; i++) {
            if(s.charAt(i) == s.charAt(i + 1)) {
                return false;
            }
        }
        return true;
    }

}

import java.util.*;

public class Solution {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

int len = in.nextInt();

String s = in.next();

Set<Character> distinct = new HashSet<>();

for (int i = 0; i < len; i++) {

distinct.add(s.charAt(i));

}

List<Character> distinctList = new ArrayList<>(distinct);

int max = 0;

for(int i = 0; i < distinct.size() - 1; i++) {

for(int j = i + 1; j < distinct.size() ; j++) {

char c1 = distinctList.get(i);

char c2 = distinctList.get(j);

String subset = s.replaceAll("[^" + c1 + "" + c2 + "]", "");

if(isAlternating(subset)) {

int l = subset.length();

max = l > max ? l : max;

}

System.out.println(max);

}

private static boolean isAlternating(String s) {

for(int i = 0; i < s.length() - 1; i++) {

if(s.charAt(i) == s.charAt(i + 1)) {

return false;

}

return true;

}

Javascript

process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function isAlternating(s) {
    for(let i = 0; i < s.length - 1; i++) {
        if(s.charAt(i) == s.charAt(i + 1)) {
            return false;
        }
    }
    return true;
}

function maxLen(n, s){
    var distinct = {};
    for (var i = 0; i < n; i++) {
        distinct[s[i]] = 1;
    }

    distinct = Object.keys(distinct);

    var max = 0;
    for(var i = 0; i < distinct.length - 1; i++) {
        for(var j = i + 1; j < distinct.length ; j++) {
            var c1 = distinct[i];
            var c2 = distinct[j];
            var subset = s.replace(new RegExp('[^' + c1 + '' + c2 + ']', "gi"), '');

            if(isAlternating(subset)) {
                var l = subset.length;
                max = l > max ? l : max;
            }
        }
    }

    return max;
}

function main() {
    var n = parseInt(readLine());
    var s = readLine();
    var result = maxLen(n, s);
    process.stdout.write(""+result+"\n");

}

process.stdin.resume();

process.stdin.setEncoding('ascii');

var input_stdin = "";

var input_stdin_array = "";

var input_currentline = 0;

process.stdin.on('data', function (data) {

input_stdin += data;

});

process.stdin.on('end', function () {

input_stdin_array = input_stdin.split("\n");

main();

});

function readLine() {

return input_stdin_array[input_currentline++];

}

/////////////// ignore above this line ////////////////////

function isAlternating(s) {

for(let i = 0; i < s.length - 1; i++) {

if(s.charAt(i) == s.charAt(i + 1)) {

return false;

}

return true;

}

function maxLen(n, s){

var distinct = {};

for (var i = 0; i < n; i++) {

distinct[s[i]] = 1;

}

distinct = Object.keys(distinct);

var max = 0;

for(var i = 0; i < distinct.length - 1; i++) {

for(var j = i + 1; j < distinct.length ; j++) {

var c1 = distinct[i];

var c2 = distinct[j];

var subset = s.replace(new RegExp('[^' + c1 + '' + c2 + ']', "gi"), '');

if(isAlternating(subset)) {

var l = subset.length;

max = l > max ? l : max;

}

return max;

}

function main() {

var n = parseInt(readLine());

var s = readLine();

var result = maxLen(n, s);

process.stdout.write(""+result+"\n");

}

Pavol Pidanič

I can count to 1023 with 10 fingers

Hackerrank – Two Characters

Hackerrank – Problem Statement

Solution

Scala

Java

Javascript

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