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Merged
realDuYuanChao merged 2 commits into from
Aug 16, 2020
Merged

Added Sum Of Digits Algorithm #1418

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b4839c2
Added SumOfDigits
realDuYuanChao Aug 16, 2020
f9ae088
updating DIRECTORY.md
Aug 16, 2020
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3 changes: 2 additions & 1 deletion DIRECTORY.md
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Original file line number Diff line number Diff line change
Expand Up @@ -143,13 +143,14 @@
* [PowRecursion](https://github.com/TheAlgorithms/Java/blob/master/Maths/PowRecursion.java)
* [PrimeCheck](https://github.com/TheAlgorithms/Java/blob/master/Maths/PrimeCheck.java)
* [PrimeFactorization](https://github.com/TheAlgorithms/Java/blob/master/Maths/PrimeFactorization.java)
* [SumOfDigits](https://github.com/TheAlgorithms/Java/blob/master/Maths/SumOfDigits.java)
* [VampireNumber](https://github.com/TheAlgorithms/Java/blob/master/Maths/VampireNumber.java)

## MinimizingLateness
* [MinimizingLateness](https://github.com/TheAlgorithms/Java/blob/master/MinimizingLateness/MinimizingLateness.java)

## Misc
* [heap sort](https://github.com/TheAlgorithms/Java/blob/master/Misc/heap_sort.java)
* [HeapSort](https://github.com/TheAlgorithms/Java/blob/master/Misc/HeapSort.java)
* [MedianOfRunningArray](https://github.com/TheAlgorithms/Java/blob/master/Misc/MedianOfRunningArray.java)
* [PalindromePrime](https://github.com/TheAlgorithms/Java/blob/master/Misc/PalindromePrime.java)

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62 changes: 62 additions & 0 deletions Maths/SumOfDigits.java
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package Maths;

public class SumOfDigits {
public static void main(String[] args) {
assert
sumOfDigits(-123) == 6
&& sumOfDigitsRecursion(-123) == 6
&& sumOfDigitsFast(-123) == 6;

assert sumOfDigits(0) == 0
&& sumOfDigitsRecursion(0) == 0
&& sumOfDigitsFast(0) == 0;


assert sumOfDigits(12345) == 15
&& sumOfDigitsRecursion(12345) == 15
&& sumOfDigitsFast(12345) == 15;
}

/**
* Calculate the sum of digits of a number
*
* @param number the number contains digits
* @return sum of digits of given {@code number}
*/
public static int sumOfDigits(int number) {
number = number < 0 ? -number : number; /* calculate abs value */
int sum = 0;
while (number != 0) {
sum += number % 10;
number /= 10;
}
return sum;
}

/**
* Calculate the sum of digits of a number using recursion
*
* @param number the number contains digits
* @return sum of digits of given {@code number}
*/
public static int sumOfDigitsRecursion(int number) {
number = number < 0 ? -number : number; /* calculate abs value */
return number < 10 ? number : number % 10 + sumOfDigitsRecursion(number / 10);
}

/**
* Calculate the sum of digits of a number using char array
*
* @param number the number contains digits
* @return sum of digits of given {@code number}
*/
public static int sumOfDigitsFast(int number) {
number = number < 0 ? -number : number; /* calculate abs value */
char[] digits = (number + "").toCharArray();
int sum = 0;
for (int i = 0; i < digits.length; ++i) {
sum += digits[i] - '0';
}
return sum;
}
}