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Add New String Interleave Class and Tests (#2032)

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* added an Interleave class

* added interleaving sequence url

* Fixes: #2031

Co-authored-by: u6943702 <u6943702@anu.edu.au>
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Phillip 2020-11-19 05:08:24 +11:00 committed by GitHub
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src/main/java/com/string/Interleave.java Normal file
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package com.string;
import org.junit.Test;
import java.util.ArrayList;
import java.util.List;
import static org.junit.Assert.assertEquals;
public class Interleave {
@Test
public void testInterleaveRegularString() {
String string1 = "Hello";
String string2 = "World";
String expected = "HWeolrllod";
String actual = interleave(string1, string2);
assertEquals("Incorrect result from method.", expected, actual);
}
@Test
public void testInterleaveEmptyString() {
String string1 = "";
String string2 = "";
String string3 = "a";
String string4 = "abc";
String expected1 = "";
String actual1 = interleave(string1, string2);
String expected2 = "a";
String actual2 = interleave(string1, string3);
String expected3 = "abc";
String actual3 = interleave(string1, string4);
assertEquals("Incorrect result from method.", expected1, actual1);
assertEquals("Incorrect result from method.", expected2, actual2);
assertEquals("Incorrect result from method.", expected3, actual3);
}
@Test
public void testInterleaveSingleString() {
String string1 = "a";
String string2 = "b";
String expected = "ab";
String actual = interleave(string1, string2);
assertEquals("Incorrect result from method.", expected, actual);
}
@Test
public void testInterleaveIntString() {
String string1 = "1";
String string2 = "7";
String expected = "17";
String actual = interleave(string1, string2);
assertEquals("Incorrect result from method.", expected, actual);
}
@Test
public void testInterleaveMixedString() {
String string1 = "1a2b3c4d";
String string2 = "5e6f7g8h";
String expected = "15ae26bf37cg48dh";
String actual = interleave(string1, string2);
assertEquals("Incorrect result from method.", expected, actual);
}
@Test
public void testInterleaveSymbols() {
String string1 = "a@b%c/";
String string2 = "d#e$g%.";
String expected = "ad@#be%$cg/%.";
String actual = interleave(string1, string2);
assertEquals("Incorrect result from method.", expected, actual);
}
@Test
public void testInterleaveSpaces() { // This string interleave algorithm defines a space as a valid character.
String string1 = " ";
String string2 = "a";
String string3 = "5 g";
String string4 = " 4 d ";
String expected1 = " a";
String actual1 = interleave(string1, string2);
String expected2 = "a5 g";
String actual2 = interleave(string2, string3);
String expected3 = "5 4g d ";
String actual3 = interleave(string3, string4);
assertEquals("Incorrect result from method.", expected1, actual1);
assertEquals("Incorrect result from method.", expected2, actual2);
assertEquals("Incorrect result from method.", expected3, actual3);
}
/**
* This method "interweaves" two input strings one character at a time. The first character of the
* first parameter string always starts the resulting string, unless that character is a space or is empty.
* This string interleaving method takes a space in a string (e.g. " ") into consideration.
*
* For example, if string1 = "abc" and string2 = "def", then the result would be "adbecf", as the first character
* of the string1 is 'a', then the first character of string2 is 'd', and so forth.
*
* For more information on interleaving, check out: https://en.wikipedia.org/wiki/Interleave_sequence
*
* @param string1
* @param string2
* @return string resulting from the interweaving of the two input strings; string1 and string2.
*/
public String interleave(String string1, String string2) {
String result = ""; // The final interleaved string to return.
List<Character> list1 = new ArrayList<>(); // The ArrayList of string1, with each character being an individual element.
List<Character> list2 = new ArrayList<>(); // The ArrayList of string2, in a similar manner as above.
for (int i = 0; i < string1.length(); i++) // Convert string1 into list1.
list1.add(string1.charAt(i));
for (int i = 0; i < string2.length(); i++) // Convert string2 into list2.
list2.add(string2.charAt(i));
if (string1.length() == string2.length()) { // Interleaving when string1 and string2 are equal length.
for (int j = 0; j < list1.size(); j++) {
result = result + list1.get(j);
result = result + list2.get(j);
}
return result;
}
if (string1.length() > string2.length()) { // Interleaving when string1 is longer than string2.
while (list2.size() > 0) {
result = result + list1.get(0);
list1.remove(0);
result = result + list2.get(0);
list2.remove(0);
}
for (char character : list1) { // Concatenate the rest of the characters in list1 to the result.
result = result + character;
}
return result;
}
if (string2.length() > string1.length()) { // Interleaving when string2 is longer than string1.
while (list1.size() > 0) {
result = result + list1.get(0);
list1.remove(0);
result = result + list2.get(0);
list2.remove(0);
}
for (char character : list2) { // Concatenate the rest of the characters in list2 to the result.
result = result + character;
}
return result;
}
return result;
}
}