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BAEL-7555-count-unique-digit-in-integer (#15933)

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* BAEL-7555-count-unique-digit-in-integer

* rename test case

* add solution using stream
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vunamtien 2024-03-07 00:47:29 +07:00 committed by GitHub
parent c39267bbf9
commit 2dc927ea9b
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36
algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/uniquedigit/UniqueDigitCounter.java Normal file
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package com.baeldung.algorithms.uniquedigit;
import java.util.HashSet;
import java.util.Set;
public class UniqueDigitCounter {
public static int countWithSet(int number) {
number = Math.abs(number);
Set<Character> uniqueDigits = new HashSet<>();
String numberStr = String.valueOf(number);
for (char digit : numberStr.toCharArray()) {
uniqueDigits.add(digit);
}
return uniqueDigits.size();
}
public static int countWithBitManipulation(int number) {
if (number == 0) {
return 1;
}
number = Math.abs(number);
int mask = 0;
while (number > 0) {
int digit = number % 10;
mask |= 1 << digit;
number /= 10;
}
return Integer.bitCount(mask);
}
public static long countWithStreamApi(int number) {
return String.valueOf(Math.abs(number)).chars().distinct().count();
}
}

38
algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/uniquedigit/UniqueDigitCounterUnitTest.java Normal file
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package com.baeldung.algorithms.uniquedigit;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
public class UniqueDigitCounterUnitTest {
@Test
public void givenNotNegativeNumber_whenCountUniqueDigits_thenCorrectCount() {
assertEquals(3, UniqueDigitCounter.countWithSet(122333));
assertEquals(1, UniqueDigitCounter.countWithSet(0));
assertEquals(2, UniqueDigitCounter.countWithSet(101));
assertEquals(3, UniqueDigitCounter.countWithBitManipulation(122333));
assertEquals(1, UniqueDigitCounter.countWithBitManipulation(0));
assertEquals(2, UniqueDigitCounter.countWithBitManipulation(101));
assertEquals(3, UniqueDigitCounter.countWithStreamApi(122333));
assertEquals(1, UniqueDigitCounter.countWithStreamApi(0));
assertEquals(2, UniqueDigitCounter.countWithStreamApi(101));
}
@Test
public void givenNegativeNumber_whenCountUniqueDigits_thenCorrectCount() {
assertEquals(3, UniqueDigitCounter.countWithSet(-122333));
assertEquals(3, UniqueDigitCounter.countWithBitManipulation(-122333));
assertEquals(3, UniqueDigitCounter.countWithStreamApi(-122333));
}
@Test
public void givenLargeNumber_whenCountUniqueDigits_thenCorrectCount() {
assertEquals(2, UniqueDigitCounter.countWithSet(1000000000));
assertEquals(2, UniqueDigitCounter.countWithBitManipulation(1000000000));
assertEquals(2, UniqueDigitCounter.countWithStreamApi(1000000000));
}
}