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fix: handle constant inputs in `LongestIncreasingSubsequence::findLISLen' (#5160)

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fix: handle constant inputs in `LongestIncreasingSubsequence::findLISLen`
This commit is contained in:
Piotr Idzik
2024-05-17 11:54:22 +02:00
committed by GitHub
parent 0f42e995a4
commit bf9d0ed66a
2 changed files with 56 additions and 20 deletions
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27
src/main/java/com/thealgorithms/dynamicprogramming/LongestIncreasingSubsequence.java
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@ -1,7 +1,5 @@
package com.thealgorithms.dynamicprogramming;
import java.util.Scanner;
/**
* @author Afrizal Fikri (https://github.com/icalF)
*/
@ -9,20 +7,6 @@ public final class LongestIncreasingSubsequence {
private LongestIncreasingSubsequence() {
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int[] arr = new int[n];
for (int i = 0; i < n; i++) {
arr[i] = sc.nextInt();
}
System.out.println(LIS(arr));
System.out.println(findLISLen(arr));
sc.close();
}
private static int upperBound(int[] ar, int l, int r, int key) {
while (l < r - 1) {
int m = (l + r) >>> 1;
@ -36,7 +20,7 @@ public final class LongestIncreasingSubsequence {
return r;
}
private static int LIS(int[] array) {
public static int LIS(int[] array) {
int N = array.length;
if (N == 0) {
return 0;
@ -73,14 +57,17 @@ public final class LongestIncreasingSubsequence {
*/
// A function for finding the length of the LIS algorithm in O(nlogn) complexity.
public static int findLISLen(int[] a) {
int size = a.length;
final int size = a.length;
if (size == 0) {
return 0;
}
int[] arr = new int[size];
arr[0] = a[0];
int lis = 1;
for (int i = 1; i < size; i++) {
int index = binarySearchBetween(arr, lis, a[i]);
int index = binarySearchBetween(arr, lis - 1, a[i]);
arr[index] = a[i];
if (index > lis) {
if (index == lis) {
lis++;
}
}

49
src/test/java/com/thealgorithms/dynamicprogramming/LongestIncreasingSubsequenceTests.java Normal file
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@ -0,0 +1,49 @@
package com.thealgorithms.dynamicprogramming;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Stream;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;
public class LongestIncreasingSubsequenceTests {
@FunctionalInterface
public interface IntArrayToInt {
int apply(int[] array);
}
@ParameterizedTest
@MethodSource("testCases")
public void testLongestIncreasingSubsequence(final int expected, final int[] input, final IntArrayToInt method) {
assertEquals(expected, method.apply(input));
}
private static Stream<Arguments> testCases() {
final Object[][] testData = {
{0, new int[] {}},
{1, new int[] {1}},
{1, new int[] {2, 2}},
{1, new int[] {3, 3, 3}},
{1, new int[] {4, 4, 4, 4}},
{1, new int[] {5, 5, 5, 5, 5}},
{2, new int[] {1, 2}},
{2, new int[] {1, 2, 2, 2, 2}},
{2, new int[] {1, 0, 2}},
{3, new int[] {1, 10, 2, 30}},
{3, new int[] {5, 8, 3, 7, 9, 1}},
{6, new int[] {0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15}},
{4, new int[] {10, 9, 2, 5, 3, 7, 101, 18}},
{4, new int[] {10, 10, 9, 9, 2, 2, 5, 5, 3, 3, 7, 7, 101, 101, 18, 18}},
{4, new int[] {0, 1, 0, 3, 2, 3}},
{2, new int[] {1, 1, 2, 2, 2}},
{3, new int[] {1, 1, 2, 2, 2, 3, 3, 3, 3}},
};
final List<IntArrayToInt> methods = Arrays.asList(LongestIncreasingSubsequence::LIS, LongestIncreasingSubsequence::findLISLen);
return Stream.of(testData).flatMap(input -> methods.stream().map(method -> Arguments.of(input[0], input[1], method)));
}
}