36 lines
1.0 KiB
Java
36 lines
1.0 KiB
Java
package Maths;
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/**
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* <p>
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* In number theory, the aliquot sum s(n) of a positive integer n is the sum of all proper divisors of n,
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* that is, all divisors of n other than n itself.
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* For example, the proper divisors of 15 (that is, the positive divisors of 15 that are not equal to 15)
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* are 1, 3 and 5, so the aliquot sum of 15 is 9 i.e. (1 + 3 + 5).
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* </p>
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* Wikipedia: https://en.wikipedia.org/wiki/Aliquot_sum
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*/
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public class AliquotSum {
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public static void main(String[] args) {
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assert aliquotSum(1) == 0;
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assert aliquotSum(6) == 6;
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assert aliquotSum(15) == 9;
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assert aliquotSum(19) == 1;
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}
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/**
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* Finds the aliquot sum of an integer number
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*
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* @param number a positive integer
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* @return aliquot sum of given {@code number}
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*/
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public static int aliquotSum(int number) {
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int sum = 0;
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for (int i = 1, limit = number / 2; i <= limit; ++i) {
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if (number % i == 0) {
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sum += i;
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}
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}
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return sum;
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}
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}
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