Change project structure to a Maven Java project + Refactor (#2816)

src/main/java/com/thealgorithms/maths/AliquotSum.java

@@ -0,0 +1,34 @@
+package com.thealgorithms.maths;
+
+/**
+ * In number theory, the aliquot sum s(n) of a positive integer n is the sum of
+ * all proper divisors of n, that is, all divisors of n other than n itself. For
+ * example, the proper divisors of 15 (that is, the positive divisors of 15 that
+ * are not equal to 15) are 1, 3 and 5, so the aliquot sum of 15 is 9 i.e. (1 +
+ * 3 + 5). Wikipedia: https://en.wikipedia.org/wiki/Aliquot_sum
+ */
+public class AliquotSum {
+
+    public static void main(String[] args) {
+        assert aliquotSum(1) == 0;
+        assert aliquotSum(6) == 6;
+        assert aliquotSum(15) == 9;
+        assert aliquotSum(19) == 1;
+    }
+
+    /**
+     * Finds the aliquot sum of an integer number
+     *
+     * @param number a positive integer
+     * @return aliquot sum of given {@code number}
+     */
+    public static int aliquotSum(int number) {
+        int sum = 0;
+        for (int i = 1, limit = number / 2; i <= limit; ++i) {
+            if (number % i == 0) {
+                sum += i;
+            }
+        }
+        return sum;
+    }
+}