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Add LongestCommonPrefix (#5849)

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This commit is contained in:
Ramit Gangwar (NoiR)
2024-10-27 00:31:47 +05:30
committed by GitHub
parent 84522baa92
commit 3da16a7fe0
3 changed files with 97 additions and 0 deletions
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2
DIRECTORY.md
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@ -686,6 +686,7 @@
* [Isomorphic](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Isomorphic.java)
* [KMP](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/KMP.java)
* [LetterCombinationsOfPhoneNumber](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/LetterCombinationsOfPhoneNumber.java)
* [LongestCommonPrefix](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/LongestCommonPrefix.java)
* [LongestNonRepetitiveSubstring](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/LongestNonRepetitiveSubstring.java)
* [LongestPalindromicSubstring](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/LongestPalindromicSubstring.java)
* [Lower](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Lower.java)
@ -1311,6 +1312,7 @@
* [HorspoolSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/HorspoolSearchTest.java)
* [IsomorphicTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/IsomorphicTest.java)
* [LetterCombinationsOfPhoneNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/LetterCombinationsOfPhoneNumberTest.java)
* [LongestCommonPrefixTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/LongestCommonPrefixTest.java)
* [LongestNonRepetitiveSubstringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/LongestNonRepetitiveSubstringTest.java)
* [LongestPalindromicSubstringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/LongestPalindromicSubstringTest.java)
* [LowerTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/LowerTest.java)

22
src/main/java/com/thealgorithms/strings/LongestCommonPrefix.java Normal file
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package com.thealgorithms.strings;
import java.util.Arrays;
public final class LongestCommonPrefix {
public String longestCommonPrefix(String[] strs) {
if (strs == null || strs.length == 0) {
return "";
}
Arrays.sort(strs);
String shortest = strs[0];
String longest = strs[strs.length - 1];
int index = 0;
while (index < shortest.length() && index < longest.length() && shortest.charAt(index) == longest.charAt(index)) {
index++;
}
return shortest.substring(0, index);
}
}

73
src/test/java/com/thealgorithms/strings/LongestCommonPrefixTest.java Normal file
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package com.thealgorithms.strings;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
public class LongestCommonPrefixTest {
private final LongestCommonPrefix longestCommonPrefix = new LongestCommonPrefix();
@Test
public void testCommonPrefix() {
String[] input = {"flower", "flow", "flight"};
String expected = "fl";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testNoCommonPrefix() {
String[] input = {"dog", "racecar", "car"};
String expected = "";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testEmptyArray() {
String[] input = {};
String expected = "";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testNullArray() {
String[] input = null;
String expected = "";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testSingleString() {
String[] input = {"single"};
String expected = "single";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testCommonPrefixWithDifferentLengths() {
String[] input = {"ab", "a"};
String expected = "a";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testAllSameStrings() {
String[] input = {"test", "test", "test"};
String expected = "test";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testPrefixAtEnd() {
String[] input = {"abcde", "abcfgh", "abcmnop"};
String expected = "abc";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
@Test
public void testMixedCase() {
String[] input = {"Flower", "flow", "flight"};
String expected = "";
assertEquals(expected, longestCommonPrefix.longestCommonPrefix(input));
}
}