Initial commit

.github/workflows/maven.yml

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+# This workflow will build a Java project with Maven, and cache/restore any dependencies to improve the workflow execution time
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-java-with-maven
+
+# This workflow uses actions that are not certified by GitHub.
+# They are provided by a third-party and are governed by
+# separate terms of service, privacy policy, and support
+# documentation.
+
+name: Java CI with Maven
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up JDK 11
+      uses: actions/setup-java@v3
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+        cache: maven
+    - name: Build with Maven
+      run: mvn -B clean verify --file pom.xml
+
+    # Optional: Uploads the full dependency graph to GitHub to improve the quality of Dependabot alerts this repository can receive
+    - name: Update dependency graph
+      uses: advanced-security/maven-dependency-submission-action@571e99aab1055c2e71a1e2309b9691de18d6b7d6

.gitignore

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+**/.classpath
+**/.project
+**/.settings
+**/bin/
+**/target/
+**/.eclipse-pmd
+**/.pmd
+**/.pmdruleset.xml
+**/NOTES.txt
+*.iml
+.checkstyle
+.idea/
+.project
+.~lock*
+*.kate-swp
+**/internal/*
+

LICENSE

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+MIT License
+
+Copyright (c) 2023- Markus S.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+## Java Solutions to LeetCode Problems
+
+In this repo you will find a collection of hundreds of Java solutions to [LeetCode coding problems](https://leetcode.com/problemset/).
+
+I was active on LeetCode for quite some time,<br>
+peaking in a 500-day streak of solving the daily challenge,<br>
+and even earning a free T-Shirt (which turned out too small and could not be exchanged :)
+
+<figure>
+    <img src="src/test/resources/img/my-leetcode-streak.jpeg" alt="500-Day Streak">
+</figure>
+
+This project requires Maven and Java 17.<br>
+
+It has neither compile nor run-time, only test dependencies.<br>
+Unit tests are based on JUnit 5 and *@ParameterizedTest*.<br>
+
+Most solutions have been successfully submitted.<br>
+Many come with JUnit tests using test data found in the problem descriptions.<br>
+
+Solutions are named *ProblemNNNN*, tests are named *ProblemNNNNTest*,<br>
+where *NNNN* is the problem number formatted to four digits with leading zeroes.<br>
+
+To build the project simply type: `mvn` (defaults to `mvn clean verify`)<br>
+
+- Use as you wish and as you see fit.<br>
+
+- No warranty given.<br>
+
+- No need to give credit.<br>
+
+- Hope you'll find it useful.<br>
+
+### Happy coding!
+
+<figure>
+    <img src="src/test/resources/img/my-leetcode-tee.jpeg" alt="Free Tee">
+    <figcaption>Free Tee</figcaption>
+</figure>

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.basepom</groupId>
+        <artifactId>basepom-oss</artifactId>
+        <version>59</version>
+    </parent>
+
+    <groupId>io.github.spannm</groupId>
+    <artifactId>leetcode</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <name>${project.artifactId}</name>
+    <description>Solutions to LeetCode coding problems</description>
+    <url>/~https://github.com/${developerId}/${project.artifactId}</url>
+    <inceptionYear>2023</inceptionYear>
+
+    <licenses>
+        <license>
+           <name>MIT License</name>
+           <url>${project.url}/blob/master/LICENSE</url>
+       </license>
+    </licenses>
+
+    <developers>
+        <developer>
+            <id>${developerId}</id>
+            <name>Markus S.</name>
+            <email>spannm@outlook.de</email>
+            <organizationUrl>/~https://github.com/${developerId}/</organizationUrl>
+        </developer>
+    </developers>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+
+        <project.build.systemJdk>17</project.build.systemJdk>
+        <project.build.targetJdk>17</project.build.targetJdk>
+
+        <developerId>spannm</developerId>
+
+        <dep.plugin.sortpom.version>4.0.0</dep.plugin.sortpom.version>
+
+        <dep.javapoet.version>1.13.0</dep.javapoet.version>
+        <dep.slf4j-api.version>2.1.0-alpha1</dep.slf4j-api.version>
+        <dep.junit.version>5.10.2</dep.junit.version>
+        <dep.assertj.version>3.26.0</dep.assertj.version>
+
+        <basepom.check.fail-dependency>false</basepom.check.fail-dependency>
+        <basepom.check.skip-spotbugs>true</basepom.check.skip-spotbugs>
+        <basepom.check.skip-license>true</basepom.check.skip-license>
+    </properties>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.junit</groupId>
+                <artifactId>junit-bom</artifactId>
+                <version>${dep.junit.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>com.squareup</groupId>
+            <artifactId>javapoet</artifactId>
+            <version>${dep.javapoet.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>${dep.slf4j-api.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${dep.slf4j-api.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-launcher</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${dep.assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+
+        <defaultGoal>clean verify</defaultGoal>
+
+        <pluginManagement>
+
+            <plugins>
+
+                <plugin>
+                    <artifactId>maven-checkstyle-plugin</artifactId>
+                    <configuration>
+                        <configLocation>src/test/resources/team/checkstyle-rules.xml</configLocation>
+                    </configuration>
+                </plugin>
+
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-pmd-plugin</artifactId>
+                    <configuration>
+                        <rulesets>
+                            <ruleset>src/test/resources/team/pmd-rules.xml</ruleset>
+                        </rulesets>
+                    </configuration>
+                </plugin>
+
+                <plugin>
+                    <groupId>com.github.ekryd.sortpom</groupId>
+                    <artifactId>sortpom-maven-plugin</artifactId>
+                    <version>${dep.plugin.sortpom.version}</version>
+                    <configuration>
+                        <createBackupFile>false</createBackupFile>
+                        <expandEmptyElements>false</expandEmptyElements>
+                        <nrOfIndentSpace>4</nrOfIndentSpace>
+                    </configuration>
+                </plugin>
+
+            </plugins>
+        </pluginManagement>
+
+    </build>
+
+    <profiles>
+        <profile>
+            <id>fast</id>
+            <!-- Profile to skip time-consuming steps. -->
+            <activation>
+                <activeByDefault>false</activeByDefault>
+            </activation>
+            <properties>
+                <!-- skip _compiling_ the tests -->
+                <maven.test.skip>true</maven.test.skip>
+                <!-- skip test execution -->
+                <skipTests>true</skipTests>
+
+                <maven.javadoc.skip>true</maven.javadoc.skip>
+                <basepom.check.skip-extended>true</basepom.check.skip-extended>
+            </properties>
+        </profile>
+    </profiles>
+
+</project>

src/main/java/io/github/spannm/leetcode/LeetcodeProblem.java

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+package io.github.spannm.leetcode;
+
+public abstract class LeetcodeProblem {
+
+    @Override
+    public String toString() {
+        return String.format("%s[]", getClass().getSimpleName());
+    }
+
+    public static String asString(Object _o) {
+        if (_o == null) {
+            return "null";
+        } else if (_o.getClass().isArray()) {
+            final int len = java.lang.reflect.Array.getLength(_o);
+            Object[] arr = new Object[len];
+            for (int i = 0; i < len; i++) {
+                arr[i] = java.lang.reflect.Array.get(_o, i);
+            }
+            return "["
+                + java.util.Arrays.stream(arr)
+                    .map(LeetcodeProblem::asString)
+                    .collect(java.util.stream.Collectors.joining(","))
+                + "]";
+        }
+        return _o.toString();
+    }
+
+}

src/main/java/io/github/spannm/leetcode/LeetcodeRuntimeException.java

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+package io.github.spannm.leetcode;
+
+/**
+ * Unspecific {@code Leetcode} run-time exception.
+ */
+public final class LeetcodeRuntimeException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public LeetcodeRuntimeException(String _message) {
+        this(_message, null);
+    }
+
+    public LeetcodeRuntimeException(Throwable _cause) {
+        this(null, _cause);
+    }
+
+    public LeetcodeRuntimeException(String _message, Throwable _cause) {
+        super(_message, _cause);
+    }
+
+    public static LeetcodeRuntimeException from(Throwable _ex) {
+        return _ex instanceof LeetcodeRuntimeException ? (LeetcodeRuntimeException) _ex : new LeetcodeRuntimeException(_ex);
+    }
+
+}

src/main/java/io/github/spannm/leetcode/LeetcodeSqlProblem.java

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+package io.github.spannm.leetcode;
+
+public abstract class LeetcodeSqlProblem extends LeetcodeProblem {
+
+    private final String sql;
+
+    protected LeetcodeSqlProblem(String _sql) {
+        sql = _sql;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("%s[sql=%s]", getClass().getSimpleName(), sql);
+    }
+
+}

src/main/java/io/github/spannm/leetcode/dep/BinaryMatrix.java

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+package io.github.spannm.leetcode.dep;
+
+import java.util.List;
+
+@SuppressWarnings({"PMD.ClassNamingConventions", "checkstyle:TypeNameCheck"})
+public interface BinaryMatrix {
+    int get(int _row, int _col);
+
+    List<Integer> dimensions();
+}

src/main/java/io/github/spannm/leetcode/dep/GridMaster.java

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+package io.github.spannm.leetcode.dep;
+
+@SuppressWarnings({"PMD.ClassNamingConventions", "checkstyle:TypeNameCheck"})
+public interface GridMaster {
+    boolean canMove(char _d);
+
+    int move(char _d);
+
+    boolean isTarget();
+}