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Added BigInteger to karprekar number #2899

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Merged
merged 5 commits into from
Jan 12, 2022
Merged

Added BigInteger to karprekar number #2899

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ec421fa
Added kaprekarNumberInRange
subhroacharjee Jan 4, 2022
fc5aaf0
Merge branch 'master' into master
siriak Jan 7, 2022
dc12575
Merge branch 'TheAlgorithms:master' into master
subhroacharjee Jan 8, 2022
24fd612
added bigNumber support for kaprekar number
subhroacharjee Jan 8, 2022
097040d
Merge branch 'master' into master
siriak Jan 12, 2022
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33 changes: 23 additions & 10 deletions src/main/java/com/thealgorithms/maths/KaprekarNumbers.java
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
package com.thealgorithms.maths;
import java.math.BigInteger;
import java.util.*;

public class KaprekarNumbers {
Expand All @@ -21,19 +22,31 @@ public static ArrayList<Long> kaprekarNumberInRange(long start, long end) throws
}

// Checks whether a given number is Kaprekar Number or not
public static boolean isKaprekarNumber(long number) {
long numberSquared = number * number;
if(Long.toString(number).length() == Long.toString(numberSquared).length()){
return (number == numberSquared);
public static boolean isKaprekarNumber(long num) {
String number = Long.toString(num);
BigInteger originalNumber = new BigInteger(number);
BigInteger numberSquared = originalNumber.multiply(originalNumber);
if(number.length() == numberSquared.toString().length()){
return number.equals(numberSquared.toString());
}
else{
long leftDigits1 = 0, leftDigits2;
if(Long.toString(numberSquared).contains("0")){
leftDigits1 = Long.parseLong(Long.toString(numberSquared).substring(0, Long.toString(numberSquared).indexOf("0")));
BigInteger leftDigits1 = new BigInteger("0");
BigInteger leftDigits2;
if(numberSquared.toString().contains("0")){
leftDigits1 = new BigInteger(
numberSquared.toString().
substring(0, numberSquared.toString().indexOf("0")
)
);
}
leftDigits2 = Long.parseLong(Long.toString(numberSquared).substring(0, (Long.toString(numberSquared).length() - Long.toString(number).length())));
long rightDigits = Long.parseLong(Long.toString(numberSquared).substring(Long.toString(numberSquared).length() - Long.toString(number).length()));
return (number == (leftDigits1 + rightDigits)) || (number == (leftDigits2 + rightDigits));
leftDigits2 = new BigInteger(
numberSquared.toString()
.substring(0, (numberSquared.toString().length() - number.length()))
);
BigInteger rightDigits = new BigInteger(numberSquared.toString().substring(numberSquared.toString().length() - number.length()));
String x = leftDigits1.add(rightDigits).toString();
String y = leftDigits2.add(rightDigits).toString();
return (number.equals(x)) || (number.equals(y));
}
}

Expand Down
14 changes: 13 additions & 1 deletion src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
package com.thealgorithms.maths;

import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import static org.junit.jupiter.api.Assertions.*;

public class KaprekarNumbersTest {
Expand Down Expand Up @@ -55,4 +55,16 @@ void testFor98()
assertFalse(KaprekarNumbers.isKaprekarNumber(98));
}

@Test
void testForRangeOfNumber() { try {
ArrayList<Long> rangedNumbers = KaprekarNumbers.kaprekarNumberInRange(1,100000);
long[] allTheNumbers = {1, 9, 45, 55, 99, 297, 703, 999, 2223, 2728, 4950, 5050, 7272, 7777, 9999, 17344, 22222, 77778, 82656, 95121, 99999};
for (long i:allTheNumbers) {
assert rangedNumbers.contains(i);
}
} catch (Exception e) {
assert false;
}
}

}