Daniel Lawson Chapter 5 Exercises 2-24 even

//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 2
/**
 * Created by Daniel on 5/6/2016.
 */
public class exercise2 {
    public static void main(String[] args){
        System.out.println(GDC(64,8));
    }
    public static int GDC(int a, int b){
        int n = 0;
        for(int i = Math.max(Math.abs(a),Math.abs(b));i>=1;i--)if(a%i == 0&& b%i == 0)n = Math.max(n,i);
        return n;
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 4
/**
 * Created by Daniel on 5/6/2016.
 */
import java.util.*;
public class exercise4 {
    public static void main(String[] args){
        randomX();
    }
    public static void randomX(){
        Random r = new Random();
        int random = 0;
        while(!(random>=16)){
            random = r.nextInt(16) + 5;
            for(int i = 1; i <= random; i++){
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 6
/**
 * Created by Daniel on 5/6/2016.
 */
import java.util.*;
public class exercise6 {
    public static void main(String[] args){
        makeGuesses();
    }
    public static void makeGuesses(){
        int g = 0;
        int c = 0;
        Random r = new Random();
        while(g<48){
            g = r.nextInt(50)+1;
            c++;
            System.out.printf("guess = %d\n",g);
        }
        System.out.printf("total guesses = %d\n",c);
    }

}

//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 8
/**
 * Created by Daniel on 5/8/2016.
 */
import java.util.*;
public class exercise8 {
    public static void main(String[] args){
        randomWalk();
    }
    public static void randomWalk(){
        Random r = new Random();
        int p = 0;
        int m = 0;
        while(Math.abs(p)<3){
            if(r.nextInt(2)==1)p+=1;
            else p-=1;
            System.out.printf("position = %2d\n", p);
            m = Math.max(m,p);
        }
        System.out.printf("max position = %2d",m);
    }


}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 10
/**
 * Created by Daniel on 5/8/2016.
 */
import java.util.*;
public class exercise10 {
    public static void main(String[] args){
        hopscotch(3);
    }
    public static void hopscotch(int h){
        if(h>=0)System.out.println("   1  ");
        int n = 1;
        for(int i = 1; i<=h; i++){
            n++;
            int s = new String("" + n).length() + new String("" +(n+1)).length();
            System.out.print(n);
            for(int j = 1;j<=7-s; j++)System.out.print(" ");
            System.out.println(n+1);
            n+=2;
            System.out.printf("%4d\n",n);
        }

    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 12
/**
 * Created by Daniel on 5/8/2016.
 */
import java.util.*;
public class exercise12 {
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        printAverage(s);
    }
    public static void printAverage(Scanner s){
        double n = 0;
        int c = 0;
        int m = 0;
        System.out.print("Type a number: ");
        n = s.nextDouble();
        while(n>=0){
            m+= n;
            c++;
            System.out.print("Type a number: ");
            n = s.nextDouble();
        }
       if(c>0)System.out.println("Average was " + (m/c));
        else System.out.println("Average was 0");
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 14
/**
 * Created by Daniel on 5/8/2016.
 */
public class Exercise14 {
    public static void main(String[] args){
       System.out.println(hasMidpoint(2,5,8));
    }
    public static boolean hasMidpoint(int n1,int n2, int n3){
        int small = Math.min(n1,Math.min(n2,n3));
        int  big  = Math.max(n1,Math.max(n2,n3));
        int mid = n1 + n2 + n3 -big - small;
        return ((big -small)/2 + small == mid);
    }

}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 16
/**
 * Created by Daniel on 5/8/2016.
 */
public class exercise16 {
    public static void main(String[] args){
        System.out.println(anglePairs(120,60,30));
    }
    public static boolean anglePairs(int n1, int n2, int n3){
        return (n1 + n2 == 180 || n1+n3 == 180 || n2+n3 ==180) && (n1+n2 == 90||n1+n3 == 90||n2+n3==90);
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 18
/**
 * Created by Daniel on 5/8/2016.
 */
public class exercise18 {
    public static void main(String[] args){
       System.out.println(digitSum(29107));
    }
    public static int digitSum(int n){
        int s = 0;
        while(Math.abs(n)>0){
          s += n%10;
          n/=10;
        }
        return s;
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 20
/**
 * Created by Daniel on 5/8/2016.
 */
public class exercise20 {
    public static void main(String[] args){
        System.out.println(digitRange(6));
        System.out.println(digitRange(68437));
    }
    public static int digitRange(int n){
        int max = 0;
        int min = 10;
        while(Math.abs(n)>0){
            max = Math.max(max, n%10);
            min = Math.min(min, n%10);
            n/=10;
        }
        return (max - min +1);
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 22
/**
 * Created by Daniel on 5/8/2016.
 */
public class exercise22 {
    public static void main(String args[]){
        System.out.println(allDigitsOdd(135319));
        System.out.println(allDigitsOdd(915213));
    }
    public static boolean allDigitsOdd(int n){
        while(n>0){
            if((n%10)%2 == 0) return false;
            n/=10;
        }
        return true;
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
//Exercise 24
/**
 * Created by Daniel on 5/8/2016.
 */
public class exercise24 {
    public static void main(String[] args){
        System.out.println(isAllVowels("eIEiO"));
        System.out.println(isAllVowels("oink"));
        System.out.println(isAllVowels(" "));
    }
    public static boolean isAllVowels(String s) {
        for (int i = 1; i <= s.length(); i++) {
            if (Character.toLowerCase(s.charAt(i - 1)) != 'a' && Character.toLowerCase(s.charAt(i - 1)) != 'e'&&                                                        Character.toLowerCase(s.charAt(i - 1)) != 'i' && Character.toLowerCase(s.charAt(i - 1)) != 'o' && Character.toLowerCase(s.charAt(i - 1)) != 'u'&& Character.toLowerCase(s.charAt(i - 1)) != ' ') {//really long if statement
               return false;
           }
        }

        return true;
    }

}