63 lines
1.9 KiB
Java
63 lines
1.9 KiB
Java
package Maths;
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public class SumOfDigits {
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public static void main(String[] args) {
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assert
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sumOfDigits(-123) == 6
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&& sumOfDigitsRecursion(-123) == 6
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&& sumOfDigitsFast(-123) == 6;
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assert sumOfDigits(0) == 0
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&& sumOfDigitsRecursion(0) == 0
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&& sumOfDigitsFast(0) == 0;
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assert sumOfDigits(12345) == 15
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&& sumOfDigitsRecursion(12345) == 15
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&& sumOfDigitsFast(12345) == 15;
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}
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/**
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* Calculate the sum of digits of a number
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*
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* @param number the number contains digits
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* @return sum of digits of given {@code number}
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*/
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public static int sumOfDigits(int number) {
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number = number < 0 ? -number : number; /* calculate abs value */
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int sum = 0;
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while (number != 0) {
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sum += number % 10;
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number /= 10;
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}
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return sum;
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}
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/**
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* Calculate the sum of digits of a number using recursion
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*
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* @param number the number contains digits
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* @return sum of digits of given {@code number}
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*/
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public static int sumOfDigitsRecursion(int number) {
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number = number < 0 ? -number : number; /* calculate abs value */
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return number < 10 ? number : number % 10 + sumOfDigitsRecursion(number / 10);
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}
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/**
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* Calculate the sum of digits of a number using char array
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*
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* @param number the number contains digits
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* @return sum of digits of given {@code number}
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*/
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public static int sumOfDigitsFast(int number) {
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number = number < 0 ? -number : number; /* calculate abs value */
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char[] digits = (number + "").toCharArray();
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int sum = 0;
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for (int i = 0; i < digits.length; ++i) {
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sum += digits[i] - '0';
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}
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return sum;
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}
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}
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