Lists and arrays

ListsAndArrays/src/AccountBook.java

@@ -1,11 +1,44 @@
 
 public class AccountBook {
 //intermediate (multidimensional arrays)
-
 	//todo: a bank will give you 2% interest on your savings stored on an account book.
 	//for a certain amount of money you want to store in the account book create a multidimensional array where
 	//the interest of the next 10 years is stored.
 	//For that save the year and the amount of money. Write a method which takes a certain year as input (e.g. 2019) and an amount of money you would like to store
 	//and returns the saving you would have for this year.
 
+public static double[][] accountBook(double y) {
+	double x[][] = new double[11][2];
+	double year = 2017.0;
+	x[0][0] = year;
+	x[0][1] = y;
+	for (int i=1; i<11; i++) {
+		year = year + 1;
+		x[i][0] = year;
+		for (int j=1; j<2; j++ ) {
+			x[i][j] = x[i -1][j] + x[i -1][j]*0.02;
+		}
+	}
+	return x;
+}
+
+public static void money(double x[][], double y) {
+	for (int i=0; i<x.length; i++) {
+		for (int j= 0; j<x[i].length; j++) {
+			if (x[i][j] == y) {
+				System.out.println("The ammount of money in year " + x[i][j] + " will be " + x[i][(j + 1)]);
+			}
+		}
+	}
+}
+
+public static void main(String[] args) {
+	double x[][] = accountBook(100.0);
+	for (int i=0; i<x.length; i++) {
+		for (int j=0; j<x[i].length; j++) {
+			System.out.println(x[i][j]);
+		}
+	}
+	money(x, 2026);
+}
 }

ListsAndArrays/src/Basics.java

@@ -2,6 +2,45 @@
 public class Basics {
 //beginner
 
+	public static void length(int[] x) {
+		System.out.println("The length of the array is: " + x.length);
+
+	}
+
+	public static void dropElement(int[] x) {
+		int y[]  = new int[x.length -1];
+		for (int i = 0; i < y.length; i++) {
+			y[i] = x[i];
+		}
+		for (int i = 0; i < y.length; i++) {
+			System.out.println("Array is now x[" + i + "]: " + y[i]);	
+		}
+
+	}
+
+	public static void sum(int[] x) {
+		int sum = 0;
+		for (int i = 0; i < x.length; i++) {
+			sum += x[i];
+		}
+		System.out.println("The sum of of all elements of the array is: " + sum);
+	}
+
+	public static void check(int x[], int element) {
+		for (int i = 0; i < x.length; i++) {
+			if (x[i] == element) {
+				System.out.println("The " + element + " is in row " + i); 
+			} 
+		}
+	}
+
+	public static void main(String[] args) {
+		int[] x = {2, 5, 7, 8, 9, 25, 55};
+		length(x);
+		dropElement(x);
+		sum(x);
+		check(x, 9);
+	}
 	//todo: write some methods for some basic operations with arrays, like:
 	//-return the length of an array
 	//-drop the last element of an array

ListsAndArrays/src/BasicsArrayList.java

@@ -1,9 +1,30 @@
-
+import java.util.*;
 public class BasicsArrayList {
 //beginner
 
 	//todo: write some methods for basic operations with ArrayLists:
 	//-write a method where you can add a certain value to an ArrayList
 	//-write a method which prints all the values in an ArrayList
+
+public static List addlist(List l, int x) {
+	Integer y = new Integer(x); 
+	l.add(y);
+	return l;
+}
 
+public static void prlist(List l) {
+	for (Object o: l) {
+		System.out.println(o);
+	}
+}
+
+public static void main(String[] args) {
+	List list = new ArrayList();
+	Integer i = new Integer(5);
+	Integer j = new Integer(8);
+	list.add(i);
+	list.add(j);
+	addlist(list, 10);
+	prlist(list);
+}
 }

ListsAndArrays/src/BubbleSort.java

@@ -1,7 +1,26 @@
 
 public class BubbleSort {
 //intermediate
+	public static int[] bubbleSort(int x[]) {
+		for (int i = 0; i < x.length; i++) {
+			for (int j = 1; j < (x.length - 1); j++) {
+				if (x[j - 1] > x[j]) {
+					int a = x[j];
+					x[j] = x[j - 1];
+					x[j - 1] = a;
+				}
+			}
+		}	
+		return x;
+	}
 
+	public static void main(String[] args) {
+		int[] x = {2, 15, 4, 8, 22, 30};
+		bubbleSort(x);
+		for (int i = 0; i < x.length; i++) {
+		System.out.print(x[i] + " ");
+		}
+	}
 	//todo: sort an array using bubblesort.
 	//if you don't know how bubblesort works you can read it here: http://www.pkirs.utep.edu/CIS3355/Tutorials/chapter9/tutorial9A/bubblesort.htm
 

Methods/src/Circle.java

@@ -1,5 +1,33 @@
+import java.util.Scanner;
 
 public class Circle {
 	//todo: add some methods to compute a circle's diameter, circumference and area.
 	//print some outputs to confirm you methods are working right.
+	public static double diameter(double r) {
+		double d = 2 * r;
+		return  d;
+	}
+
+	public static double circ(double r) {
+		double pi = Math.PI ;
+		double c = 2 * pi * r ;
+		return c ;
+	}
+
+	public static double area(double r) {
+		double pi = Math.PI ;
+		double a = pi * r * r ;
+		return a ;
+	}
+
+	public static void main(String[] args) {
+
+		Scanner scan = new Scanner(System.in);
+		System.out.println("Radius: ");
+		Double r = scan.nextDouble();
+
+		System.out.println(diameter(r));
+		System.out.println(circ(r));
+		System.out.println(area(r));
+	}
 }

Methods/src/Prime.java

@@ -3,9 +3,30 @@
 
 public class Prime {
 
+	public static boolean prime(int n) {
+
+		if (n <= 1) {
+			return false;
+		} else if (n <= 3 ) {
+			return true;
+		} else if (n % 2 == 0 || n % 3 == 0) {
+			return false;
+		} else {
+			for (int i = 5; i * i <= n; i = i + 6 ) {
+				if (n % i == 0 || n % (i + 2) == 0) {
+					return false; 
+				}
+			return true;
+			} 
+		} return true; 
+	}
+
 	public static void main(String[] args) {
+
 		Scanner scan = new Scanner(System.in);
+		int n = scan.nextInt(); 
 
+		System.out.println("The number " + n + " is prime: " + prime(n));
 		//todo: write a method which tells you if a given number is a prime or not
 
 	}

Recursion/src/Factorial.java

@@ -1,4 +1,21 @@
+import java.util.Scanner;
 
 public class Factorial {
 	//todo: implement a recursive functions whicht gives you the factorial value of a given number
+	public static int factorial(int x) {
+		if (x <= 1) {
+			return 1;
+		} else {
+			return x * factorial(x -1);
+
+		}
+	}
+
+	public static void main (String[] args) {
+		Scanner scan = new Scanner(System.in);
+		int x = scan.nextInt(); 
+
+		System.out.println("The factorial of number " + x + " is: " + factorial(x));
+	}
 }
+

Recursion/src/Fibonacci.java

@@ -1,5 +1,21 @@
-
+import java.util.Scanner;
 public class Fibonacci {
 	//todo: implement a recursive function which takes an integer value as inputs and outputs the corresponding Fibonacci number.
 	//if you don't know what Fibonacci numbers are you can read it here: https://en.wikipedia.org/wiki/Fibonacci_number
+public static int placeFibonacci(int n) {
+	if (n == 0 || n == 1) {
+		return n;
+	} else {
+		return placeFibonacci(n - 2) + placeFibonacci(n - 1);
+	}
+}
+
+public static void main (String[] args) {
+	Scanner scan = new Scanner(System.in);
+	int n = scan.nextInt();
+
+	System.out.println("At the place" + n + " of the Fibonacci list, is the number: " + placeFibonacci(n));
 }
+
+}
+

Structures/src/AssignGrade.java

@@ -6,7 +6,16 @@ public class AssignGrade {
 
 	public static void main(String[] args) {
 		Scanner scan = new Scanner(System.in);
+		System.out.println("Score: ");
+		int score = scan.nextInt();
 
+		double grade = ((100 - score)/50.0) * 3 + 1;
+
+		 if (grade <= 4.0) {
+			System.out.println("Pass with grade: " + grade);
+		} else {
+			System.out.println("Fail with grade: " + grade);
+		} 
 		//todo: when executing the program you will be ask to write a score.
 		//The program converts the score then into a grade and prints that grade (1.0, 1.3, 1.7, ...)
 		//Note that the student passed when the student gets a score of 50.0 points (4.0)

Structures/src/EvenOdd.java

@@ -6,6 +6,16 @@ public class EvenOdd {
 
 	public static void main(String[] args) {
 		Scanner scan = new Scanner(System.in);
+		System.out.println("Number: ");
+		int number = scan.nextInt();
+
+
+		for (int count = 0; count < number; count ++) {
+			if (count % 2 != 0) {
+				System.out.println(count);
+			}
+		}
+
 
 		//todo: The program takes a number as input.
 		//It then goes through all integer values till reaching that value and prints all the odd ones.