diff --git a/Maths/AmicableNumber.java b/Maths/AmicableNumber.java new file mode 100644 index 00000000..1d81a393 --- /dev/null +++ b/Maths/AmicableNumber.java @@ -0,0 +1,87 @@ +package Maths; + +/** + * Amicable numbers are two different numbers so related + * that the sum of the proper divisors of each is equal to the other number. + * (A proper divisor of a number is a positive factor of that number other than the number itself. + * For example, the proper divisors of 6 are 1, 2, and 3.) + * A pair of amicable numbers constitutes an aliquot sequence of period 2. + * It is unknown if there are infinitely many pairs of amicable numbers. + * * + *

+ * * link: https://en.wikipedia.org/wiki/Amicable_numbers + * *

+ *

+ * Simple Example : (220,284) 220 is divisible by {1,2,4,5,10,11,20,22,44,55,110 } <- Sum = 284 + * 284 is divisible by -> 1,2,4,71,142 and the Sum of that is. Yes right you probably expected it 220 + */ + +public class AmicableNumber { + + public static void main(String[] args) { + + AmicableNumber.findAllInRange(1,3000); + /* Res -> Int Range of 1 till 3000there are 3Amicable_numbers These are 1: = ( 220,284) 2: = ( 1184,1210) + 3: = ( 2620,2924) So it worked */ + + } + + /** + * @param startValue + * @param stopValue + * @return + */ + static void findAllInRange(int startValue, int stopValue) { + + /* the 2 for loops are to avoid to double check tuple. For example (200,100) and (100,200) is the same calculation + * also to avoid is to check the number with it self. a number with itself is always a AmicableNumber + * */ + StringBuilder res = new StringBuilder(); + int countofRes = 0; + + for (int i = startValue; i < stopValue; i++) { + for (int j = i + 1; j <= stopValue; j++) { + if (isAmicableNumber(i, j)) { + countofRes++; + res.append("" + countofRes + ": = ( " + i + "," + j + ")" + "\t"); + } + } + } + res.insert(0, "Int Range of " + startValue + " till " + stopValue + " there are " + countofRes + " Amicable_numbers.These are \n "); + System.out.println(res.toString()); + } + + /** + * Check if {@code numberOne and numberTwo } are AmicableNumbers or not + * + * @param numberOne numberTwo + * @return {@code true} if {@code numberOne numberTwo} isAmicableNumbers otherwise false + */ + static boolean isAmicableNumber(int numberOne, int numberTwo) { + + return ((recursiveCalcOfDividerSum(numberOne, numberOne) == numberTwo && numberOne == recursiveCalcOfDividerSum(numberTwo, numberTwo))); + } + + /** + * calculated in recursive calls the Sum of all the Dividers beside it self + * + * @param number div = the next to test dividely by using the modulo operator + * @return sum of all the dividers + */ + static int recursiveCalcOfDividerSum(int number, int div) { + + if (div == 1) { + return 0; + } else if (number % --div == 0) { + return recursiveCalcOfDividerSum(number, div) + div; + } else { + return recursiveCalcOfDividerSum(number, div); + } + } + + + + + + +} diff --git a/Maths/VampireNumber.java b/Maths/VampireNumber.java new file mode 100644 index 00000000..c9518959 --- /dev/null +++ b/Maths/VampireNumber.java @@ -0,0 +1,94 @@ +package Maths; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; + +/** + n number theory, a vampire number (or true vampire number) is a composite natural number with an even number of digits, + that can be factored into two natural numbers each with half as many digits as the original number + and not both with trailing zeroes, where the two factors contain precisely + all the digits of the original number, in any order, counting multiplicity. + The first vampire number is 1260 = 21 × 60. + * * + *

+ * * link: https://en.wikipedia.org/wiki/Vampire_number + * *

+ *

+ * + */ + + + + + + + +public class VampireNumber { + + public static void main(String[] args) { + + test(10,1000); + } + + static void test(int startValue, int stopValue) { + int countofRes = 1; + StringBuilder res = new StringBuilder(); + + + for (int i = startValue; i <= stopValue; i++) { + for (int j = i; j <= stopValue; j++) { + // System.out.println(i+ " "+ j); + if (isVampireNumber(i, j,true)) { + countofRes++; + res.append("" + countofRes + ": = ( " + i + "," + j + " = " + i*j + ")" + "\n"); + } + } + } + System.out.println(res); + } + + + + + static boolean isVampireNumber(int a, int b, boolean noPseudoVamireNumbers ) { + + // this is for pseudoVampireNumbers pseudovampire number need not be of length n/2 digits for example + // 126 = 6 x 21 + if (noPseudoVamireNumbers) { + if (a * 10 <= b || b * 10 <= a) { + return false; + } + } + + String mulDigits = splitIntoDigits(a*b,0); + String faktorDigits = splitIntoDigits(a,b); + + return mulDigits.equals(faktorDigits); + } + + + +// methode to Split the numbers to Digits + static String splitIntoDigits(int num, int num2) { + + StringBuilder res = new StringBuilder(); + + ArrayList digits = new ArrayList<>(); + while (num > 0) { + digits.add(num%10); + num /= 10; + } + while (num2 > 0) { + digits.add(num2%10); + num2/= 10; + } + Collections.sort(digits); + for (int i : digits) { + res.append(i); + } + + + return res.toString(); + } +} \ No newline at end of file