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Abundant Number
An abundant number is a number for which the sum of its divisors, is larger than itself.
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package com.bethecoder.tutorials.core.special_numbers;
import java.util.ArrayList;
import java.util.List;
/**
* An abundant number has a sum of divisors that is larger than itself
*
* @author Sudhakar KV
*
*/
public class AbundantNumber {
/**
* @param args
*/
public static void main(String[] args) {
isAbundantNumber(36);
isAbundantNumber(60);
isAbundantNumber(100);
isAbundantNumber(52);
isAbundantNumber(124);
}
private static boolean isAbundantNumber(int number) {
int sumOfDevisors = 0;
List<Integer> devisors = new ArrayList<Integer>();
for (int i = 1 ; i <= number / 2 ; i ++) {
if (number % i == 0) {
sumOfDevisors += i;
devisors.add(i);
}
}
boolean abundant = (sumOfDevisors > number);
System.err.println(number + " is " +
(abundant ? "an abundant number" : "not an abundant number") +
" " + getSum(devisors, sumOfDevisors));
return abundant;
}
private static String getSum(List<Integer> devisors, int sumOfDevisors) {
StringBuilder sb = new StringBuilder("[ ");
for (int i = 0 ; i < devisors.size(); i ++) {
if (i > 0) {
sb.append(" + ");
}
sb.append(devisors.get(i));
}
sb.append(" = ").append(sumOfDevisors).append(" ]");
return sb.toString();
}
}
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It gives the following output,
36 is an abundant number [ 1 + 2 + 3 + 4 + 6 + 9 + 12 + 18 = 55 ]
60 is an abundant number [ 1 + 2 + 3 + 4 + 5 + 6 + 10 + 12 + 15 + 20 + 30 = 108 ]
100 is an abundant number [ 1 + 2 + 4 + 5 + 10 + 20 + 25 + 50 = 117 ]
52 is not an abundant number [ 1 + 2 + 4 + 13 + 26 = 46 ]
124 is not an abundant number [ 1 + 2 + 4 + 31 + 62 = 100 ]
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