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automatic tests
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5 files changed

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‎.github/workflows/gradle.yml‎

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name: Java CI with Gradle
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on:
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push:
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branches: [ main ]
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pull_request:
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branches: [ main ]
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jobs:
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build:
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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v4
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- name: Set up JDK
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uses: actions/setup-java@v4
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with:
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distribution: 'temurin'
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java-version: 22
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cache: 'gradle'
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- name: Build with Gradle
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run: ./gradlew build

‎src/main/java/io/polypen/Parser.java‎

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package io.polypen;
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import org.apache.commons.numbers.fraction.Fraction;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import java.util.TreeMap;
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final class Parser {
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static List<Fraction> parse(String s) {
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List<SignedToken> strings = split(s.trim());
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TreeMap<Integer, Fraction> cof = new TreeMap<>();
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for (SignedToken term : strings) {
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String[] tokens = term.token.split("[a-z]", 3);
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String coefficient = tokens[0].replace("*", "").trim();
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if (coefficient.isEmpty()) {
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coefficient = "1";
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}
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if (tokens.length == 1) {
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cof.put(0, Fraction.parse(coefficient).multiply(term.sign.factor));
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} else {
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String rawExponent = tokens[1].replace("^", "").trim();
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if (rawExponent.isEmpty()) {
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cof.put(1, Fraction.parse(coefficient).multiply(term.sign.factor));
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} else {
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int exponent = Integer.parseInt(rawExponent);
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cof.put(exponent, Fraction.parse(coefficient).multiply(term.sign.factor));
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}
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}
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}
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Integer highestExponent = cof.lastKey();
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List<Fraction> result = new ArrayList<>(highestExponent);
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for (int i = 0; i <= highestExponent; i++) {
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result.add(Fraction.ZERO);
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}
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for (Map.Entry<Integer, Fraction> e : cof.entrySet()) {
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Integer exponent = e.getKey();
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Fraction coefficient = e.getValue();
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result.set(exponent, coefficient);
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}
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return result;
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}
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enum Sign {
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PLUS(1), MINUS(-1);
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final int factor;
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Sign(int factor) {
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this.factor = factor;
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}
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}
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record SignedToken(Sign sign, String token) {
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}
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private static List<SignedToken> split(String s) {
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List<SignedToken> result = new ArrayList<>();
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Sign sign = Sign.PLUS;
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int pos = -1;
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for (int i = 0; i < s.length(); i++) {
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if (s.charAt(i) == '-') {
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result.add(new SignedToken(sign, s.substring(pos + 1, i).trim()));
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sign = Sign.MINUS;
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pos = i;
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} else if (s.charAt(i) == '+') {
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result.add(new SignedToken(sign, s.substring(pos + 1, i).trim()));
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sign = Sign.PLUS;
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pos = i;
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}
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}
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if (pos < s.length() - 1) {
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result.add(new SignedToken(sign, s.substring(pos + 1).trim()));
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}
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return result;
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}
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}

‎src/main/java/io/polypen/Polynomial.java‎

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@@ -4,8 +4,8 @@
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Map;
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import java.util.TreeMap;
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import static io.polypen.Util.isAbsoluteOne;
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1010
public final class Polynomial {
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private final List<Fraction> coefficients;
@@ -14,6 +14,10 @@ private Polynomial(List<Fraction> coefficients) {
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this.coefficients = coefficients;
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}
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public static Polynomial parse(String s) {
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return new Polynomial(Parser.parse(s));
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}
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@Override
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public String toString() {
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List<String> result = new ArrayList<>(coefficients.size());
@@ -23,87 +27,18 @@ public String toString() {
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continue;
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}
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String plus = (i == coefficients.size() - 1 && coefficient.compareTo(Fraction.ZERO) > 0) ? "" : "+ ";
26-
String prettyCoefficient = coefficient.compareTo(Fraction.ZERO) < 0 ? "- " : plus;
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String prettySign = coefficient.compareTo(Fraction.ZERO) < 0 ? "- " : plus;
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if (i == 0) {
28-
result.add(prettyCoefficient + coefficient.abs());
32+
result.add(prettySign + coefficient.abs());
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} else {
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String exponent = i == 1 ? "x" : "x^" + i;
31-
if (coefficient.isOne()) {
32-
result.add(plus + exponent);
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} else if (coefficient.equals(Fraction.ONE.negate())) {
34-
result.add("- " + exponent);
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if (isAbsoluteOne(coefficient)) {
36+
result.add(prettySign + exponent);
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} else {
36-
result.add(prettyCoefficient + coefficient.abs() + " " + "x^" + i);
38+
result.add(prettySign + coefficient.abs() + " " + "x^" + i);
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}
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}
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}
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return String.join(" ", result);
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}
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43-
public static Polynomial parse(String s) {
44-
List<SignedToken> strings = split(s.trim());
45-
TreeMap<Integer, Fraction> cof = new TreeMap<>();
46-
for (SignedToken term : strings) {
47-
String[] tokens = term.token.split("[a-z]", 3);
48-
String coefficient = tokens[0].replace("*", "").trim();
49-
if (coefficient.isEmpty()) {
50-
coefficient = "1";
51-
}
52-
if (tokens.length == 1) {
53-
cof.put(0, Fraction.parse(coefficient).multiply(term.sign.factor));
54-
} else {
55-
String rawExponent = tokens[1].replace("^", "").trim();
56-
if (rawExponent.isEmpty()) {
57-
cof.put(1, Fraction.parse(coefficient).multiply(term.sign.factor));
58-
} else {
59-
int exponent = Integer.parseInt(rawExponent);
60-
cof.put(exponent, Fraction.parse(coefficient).multiply(term.sign.factor));
61-
}
62-
}
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}
64-
Integer highestExponent = cof.lastKey();
65-
List<Fraction> result = new ArrayList<>(highestExponent);
66-
for (int i = 0; i <= highestExponent; i++) {
67-
result.add(Fraction.ZERO);
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}
69-
for (Map.Entry<Integer, Fraction> e : cof.entrySet()) {
70-
Integer exponent = e.getKey();
71-
Fraction coefficient = e.getValue();
72-
result.set(exponent, coefficient);
73-
}
74-
return new Polynomial(result);
75-
}
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77-
enum Sign {
78-
PLUS(1), MINUS(-1);
79-
final int factor;
80-
81-
Sign(int factor) {
82-
this.factor = factor;
83-
}
84-
}
85-
86-
record SignedToken(Sign sign, String token) {
87-
}
88-
89-
static List<SignedToken> split(String s) {
90-
List<SignedToken> result = new ArrayList<>();
91-
Sign sign = Sign.PLUS;
92-
int pos = -1;
93-
for (int i = 0; i < s.length(); i++) {
94-
if (s.charAt(i) == '-') {
95-
result.add(new SignedToken(sign, s.substring(pos + 1, i).trim()));
96-
sign = Sign.MINUS;
97-
pos = i;
98-
} else if (s.charAt(i) == '+') {
99-
result.add(new SignedToken(sign, s.substring(pos + 1, i).trim()));
100-
sign = Sign.PLUS;
101-
pos = i;
102-
}
103-
}
104-
if (pos < s.length() - 1) {
105-
result.add(new SignedToken(sign, s.substring(pos + 1).trim()));
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}
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return result;
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}
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}

‎src/main/java/io/polypen/Util.java‎

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package io.polypen;
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import org.apache.commons.numbers.fraction.Fraction;
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final class Util {
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private static final Fraction NEGATIVE_ONE = Fraction.ONE.negate();
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static boolean isAbsoluteOne(Fraction fraction) {
9+
return fraction.isOne() || NEGATIVE_ONE.equals(fraction);
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}
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private Util() {
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}
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}

‎src/test/java/io/polypen/PolynomialTest.java‎

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@@ -2,15 +2,12 @@
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import org.junit.jupiter.api.Test;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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class PolynomialTest {
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@Test
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void parse() {
9-
System.out.println(Polynomial.parse("x^5 - x - 1"));
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}
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@Test
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void split() {
14-
System.out.println(Polynomial.split("1 + 2 - 3"));
11+
assertEquals("x^5 - x - 1", Polynomial.parse("-x + x^5 - 1").toString());
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}
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}

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