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How to Resolve Scaling Squared Strings in Java

The challenge

You are given a string of n lines, each substring being n characters long. For example:

s = "abcd\nefgh\nijkl\nmnop"

We will study the “horizontal” and the “vertical” scaling of this square of strings.

A k-horizontal scaling of a string consists of replicating k times each character of the string (except ‘\n’).

  • Example: 2-horizontal scaling of s: => “aabbccdd\neeffgghh\niijjkkll\nmmnnoopp”

A v-vertical scaling of a string consists of replicating v times each part of the squared string.

  • Example: 2-vertical scaling of s: => “abcd\nabcd\nefgh\nefgh\nijkl\nijkl\nmnop\nmnop”

Function scale(strng, k, v) will perform a k-horizontal scaling and a v-vertical scaling.

Example: a = "abcd\nefgh\nijkl\nmnop" scale(a, 2, 3) --> "aabbccdd\naabbccdd\naabbccdd\neeffgghh\neeffgghh\neeffgghh\niijjkkll\niijjkkll\niijjkkll\nmmnnoopp\nmmnnoopp\nmmnnoopp"
Code language: JavaScript (javascript)


abcd -----> aabbccdd efgh aabbccdd ijkl aabbccdd mnop eeffgghh eeffgghh eeffgghh iijjkkll iijjkkll iijjkkll mmnnoopp mmnnoopp mmnnoopp


  • Write function scale(strng, k, v) k and v will be positive integers. If strng == "" return "".

The solution in Java code

Option 1:

public class Scale { public static String scale(String s, int k, int n) { String res=""; for (String retval: s.split("\n")){ String temp=""; for (String l: retval.split("")){ temp+=new String(new char[k]).replace("\0", l); } res+=new String(new char[n]).replace("\0", temp+"\n"); } return res.trim(); } }
Code language: Java (java)

Option 2:

import; public class Scale { public static String scale(String strng, int k, int n) { String[] lines = strng.split("\n"); StringBuilder result = new StringBuilder(); IntStream.range(, lines.length).forEachOrdered(lineNumber -> { StringBuilder tmp = new StringBuilder(); lines[lineNumber].chars().forEachOrdered(c -> IntStream.range(, k).forEach(h -> tmp.append((char)c))); IntStream.range(, n).forEach(j -> result.append(tmp).append("\n")); } ); return result.toString().trim(); } }
Code language: Java (java)

Option 3:

class Scale { static String scale(String strng, int k, int v) { return strng.replaceAll("(\\w)", "$1".repeat(k)) .replaceAll("(\\w+\\n)", "$1".repeat(v)) .replaceAll("(\\n\\w+$)", "$1".repeat(v)); } }
Code language: Java (java)

Test cases to validate our solution

import static org.junit.Assert.*; import org.junit.Test; public class ScaleTest { private static void testing(String actual, String expected) { assertEquals(expected, actual); } @Test public void test() { System.out.println("Fixed Tests scale"); String a ="abcd\nefgh\nijkl\nmnop"; String r = "aabbccdd\naabbccdd\naabbccdd\neeffgghh\neeffgghh\neeffgghh\niijjkkll\n" + "iijjkkll\niijjkkll\nmmnnoopp\nmmnnoopp\nmmnnoopp"; testing(Scale.scale(a, 2, 3), r); testing(Scale.scale("", 5, 5), ""); testing(Scale.scale("Kj\nSH", 1, 2),"Kj\nKj\nSH\nSH"); } }
Code language: Java (java)

See also  Converting from Base 10 to 16 (Decimal to Hex) in Java
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