interview problems practice recursive

problems/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>
+
+    <groupId>org.interview</groupId>
+    <artifactId>problems</artifactId>
+    <version>1.0</version>
+
+    <properties>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.9.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.24.2</version>
+        </dependency>
+    </dependencies>
+
+</project>

problems/src/main/java/org/interview/recursive/palindrome/Palindrome.java

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+package org.interview.recursive.palindrome;
+
+public record Palindrome(String input) {
+    private static final int STARTING_INDEX = 0;
+    private static final int OFFSET = 1;
+
+    public boolean check() {
+        if (input.isEmpty())
+            return true;
+        return isValid(STARTING_INDEX, endingIndex());
+
+    }
+
+    public boolean isValid(int startingIndex, int endIndex) {
+        if (startingIndex >= endIndex)
+            return true;
+        if (input.charAt(startingIndex) != input.charAt(endIndex))
+            return false;
+
+        return isValid(startingIndex + OFFSET, endIndex - OFFSET);
+
+    }
+
+    private int endingIndex() {
+        return input.length() - 1;
+    }
+}

problems/src/main/java/org/interview/recursive/palindrome/explain

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+Given a string, write a recursive function that checks if the given string is a palindrome or not.
+
+Examples:
+
+Input : malayalam
+Output : Yes
+Reverse of malayalam is also
+malayalam.
+
+Input : max
+Output : No
+Reverse of max is not max.

problems/src/test/java/org/interview/recursive/PalindromeShould.java

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+package org.interview.recursive;
+
+import org.assertj.core.api.Assertions;
+import org.interview.recursive.palindrome.Palindrome;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class PalindromeShould {
+
+    @ParameterizedTest
+    @CsvSource(
+            {"ali , false",
+                    "amin ,false",
+                    "ddd , true",
+                    "aia ,true",
+                    "atda ,false",
+                    "a ,true"})
+    void chick_is_or_not(String input, boolean expected) {
+        var palindrome = new Palindrome(input);
+        Assertions.assertThat(palindrome.check()).isEqualTo(expected);
+    }
+}