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Commit1eb9dcb

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Merge pull request#1411 from shellhub/dev
update armstrong number and add NumberOfDigits
2 parentsab88fed +9a62567 commit1eb9dcb

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3 files changed

+89
-32
lines changed

3 files changed

+89
-32
lines changed

‎DIRECTORY.md‎

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*[GCDRecursion](https://github.com/TheAlgorithms/Java/blob/master/Maths/GCDRecursion.java)
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*[MaxValue](https://github.com/TheAlgorithms/Java/blob/master/Maths/MaxValue.java)
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*[MinValue](https://github.com/TheAlgorithms/Java/blob/master/Maths/MinValue.java)
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*[NumberOfDigits](https://github.com/TheAlgorithms/Java/blob/master/Maths/NumberOfDigits.java)
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*[PalindromeNumber](https://github.com/TheAlgorithms/Java/blob/master/Maths/PalindromeNumber.java)
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*[ParseInteger](https://github.com/TheAlgorithms/Java/blob/master/Maths/ParseInteger.java)
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*[PerfectNumber](https://github.com/TheAlgorithms/Java/blob/master/Maths/PerfectNumber.java)

‎Maths/NumberOfDigits.java‎

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packageMaths;
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/**
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* Find the number of digits in a number.
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*/
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publicclassNumberOfDigits {
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publicstaticvoidmain(String[]args) {
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int[]numbers = {0,12,123,1234, -12345,123456,1234567,12345678,123456789};
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for (inti =0;i <numbers.length; ++i) {
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assertnumberOfDigits(numbers[i]) ==i +1;
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assertnumberOfDigitsFast(numbers[i]) ==i +1;
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assertnumberOfDigitsFaster(numbers[i]) ==i +1;
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assertnumberOfDigitsRecursion(numbers[i]) ==i +1;
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}
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}
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/**
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* Find the number of digits in a number.
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*
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* @param number number to find
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* @return number of digits of given number
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*/
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privatestaticintnumberOfDigits(intnumber) {
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intdigits =0;
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do {
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digits++;
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number /=10;
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}while (number !=0);
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returndigits;
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}
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/**
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* Find the number of digits in a number fast version.
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*
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* @param number number to find
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* @return number of digits of given number
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*/
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privatestaticintnumberOfDigitsFast(intnumber) {
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returnnumber ==0 ?1 : (int)Math.floor(Math.log10(Math.abs(number)) +1);
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}
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/**
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* Find the number of digits in a number faster version.
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*
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* @param number number to find
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* @return number of digits of given number
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*/
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privatestaticintnumberOfDigitsFaster(intnumber) {
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returnnumber <0 ? (-number +"").length() : (number +"").length();
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}
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/**
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* Find the number of digits in a number using recursion.
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*
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* @param number number to find
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* @return number of digits of given number
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*/
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privatestaticintnumberOfDigitsRecursion(intnumber) {
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returnnumber /10 ==0 ?1 :1 +numberOfDigitsRecursion(number /10);
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}
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}

‎Others/Armstrong.java‎

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packageOthers;
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importjava.util.Scanner;
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/**
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* A utility to check if a given number is armstrong or not. Armstrong number is
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* a number that is equal to the sum of cubes of its digits for example 0, 1,
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* 153, 370, 371, 407 etc. For example 153 = 1^3 + 5^3 +3^3
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*
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* @author mani manasa mylavarapu
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* An Armstrong number is equal to the sum of the cubes of its digits.
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* For example, 370 is an Armstrong number because 3*3*3 + 7*7*7 + 0*0*0 = 370.
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* An Armstrong number is often called Narcissistic number.
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*/
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publicclassArmstrong {
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staticScannerscan;
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publicstaticvoidmain(String[]args) {
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scan =newScanner(System.in);
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intn =inputInt("please enter the number");
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booleanisArmstrong =checkIfANumberIsAmstrongOrNot(n);
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if (isArmstrong) {
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System.out.println("the number is armstrong");
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}else {
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System.out.println("the number is not armstrong");
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}
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assert (isArmStrong(0));
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assert (isArmStrong(1));
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assert (isArmStrong(153));
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assert (isArmStrong(1634));
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assert (isArmStrong(371));
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assert (!isArmStrong(200));
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}
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/**
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* Checks whether a given number is an armstrong number or not. Armstrong
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* number is a number that is equal to the sum of cubes of its digits for
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* example 0, 1, 153, 370, 371, 407 etc.
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* Checks whether a given number is an armstrong number or not.
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*
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* @param number
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* @returnboolean
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* @param number number to check
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* @return{@code true} if given number is armstrong number, {@code false} otherwise
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*/
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publicstaticbooleancheckIfANumberIsAmstrongOrNot(intnumber) {
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intremainder,sum =0,temp =0;
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temp =number;
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privatestaticbooleanisArmStrong(intnumber) {
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intsum =0;
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inttemp =number;
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intnumberOfDigits =0;
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while (temp !=0) {
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numberOfDigits++;
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temp /=10;
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}
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temp =number;/* copy number again */
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while (number >0) {
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remainder =number %10;
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sum =sum + (remainder *remainder *remainder);
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number =number /10;
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intremainder =number %10;
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intpower =1;
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for (inti =1;i <=numberOfDigits;power *=remainder, ++i) ;
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sum =sum +power;
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number /=10;
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}
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returnsum ==temp;
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}
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privatestaticintinputInt(Stringstring) {
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System.out.print(string);
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returnInteger.parseInt(scan.nextLine());
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}
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}

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