Daniel Lawson Chapter 4 Exercises 2-20 Even

//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 2
/**
 * Created by Daniel on 4/21/2016.
 */
public class Exercise2 {
    public static void main(String[] args){
        String str = repl("lol",3);
        System.out.println(str);
    }
    public static String repl(String s, int l){
        String str = "";
        for(int i = 1; i <= l; i++){
            str = str + s;
        }
        return str;
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 4
/**
 * Created by Daniel on 4/21/2016.
 */
public class Exercise4 {
    public static void main(String[] args) {
        int days = daysInMonth(4);
        System.out.println(days);
    }

    public static int daysInMonth(int m) {
    int n = 31;
    if (m == 2) n = 28;
    if (m == 4 || m == 6 || m == 9 || m == 11) n = 30;
        return n;

    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 6
/**
 * Created by Daniel on 4/21/2016.
 */
public class Exercise6 {
    public static void main(String[] args){
        printRange(19,11);
        printRange(5,5);
        printRange(2,7);
    }
    public static void printRange(int n1, int n2){
      for(int i = Math.min(n1,n2); i <= Math.max(n1,n2);i++)System.out.print(i + " ");
      System.out.println();
    }
}

//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 8
/**
 * Created by Daniel on 4/22/2016.
 */

import java.util.*;

public class Exercise8 {
    public static void main(String[] args) {
        Scanner c = new Scanner(System.in);
        smallestLargest(c);
    }

    public static void smallestLargest(Scanner c) {
        System.out.print("How many numbers do ou want to enter?");
        int n = c.nextInt();
        int min = 0;
        int max = 0;
        int num = 0;
        if(n<= 0) throw new IllegalArgumentException("You can't enter numbers <= 0!");
        for (int i = 1; i <= n; i++) {
            System.out.printf("Number %d: ", i);
            num = c.nextInt();
            max = Math.max(num,max);
            min = Math.min(num,min);
        }
        System.out.printf("Smallest = %d\n",min);
        System.out.printf("Largest = %d\n",max);

    }

}

//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 10
/**
 * Created by Daniel on 4/22/2016.
 */
import com.sun.javaws.exceptions.InvalidArgumentException;

import java.util.*;
public class Exercise10 {
    public static void main(String[] args){
        Scanner c = new Scanner(System.in);
        printGPA(c);
    }
    public static void printGPA(Scanner c){
        System.out.print("Enter a student record: ");
        String name = c.next();
        int n = c.nextInt();
        double sum = 0;
        for(int i = 1; i <= n;i++){
            double num  = c.nextDouble();
            sum += num;
        }
        sum /= n;
        System.out.printf("%s's grade is %.2f",name,sum);

    }
}

//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 12
/**
 * Created by Daniel on 4/22/2016.
 */
public class Exercise12 {
    public static void main(String[] args){
        printTriangleType(5,7,7);
        printTriangleType(6,6,6);
        printTriangleType(5,7,8);
        //printTriangleType(2,18,2); // will throw an exception
    }
    public static void printTriangleType(double s1, double s2, double s3){
        double h = Math.max(s1,s2);
        h = Math.max(h,s3);
        double s = s1 + s2 + s3 - h;
        double m = Math.min(s1,s2);
        m = Math.min(m,s3);
        if(h>s || m<= 0)throw new IllegalArgumentException("Sum of any two sides should not be lower than the third side, and side lengths should not be negative");
        String type;
       if(s1 == s2 && s1 == s3){
           type = "equilateral";
       }else if(s1 == s2 || s1 == s3 || s2 == s3){
           type = "isosceles";
       }else{
           type = "scalene";
       }
        System.out.println(type);
    }

}

//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 14
/**
 * Created by Daniel on 4/24/2016.
 */
public class Exercise14 {
    public static void main(String[] args){
       //Println statements to  test method
       System.out.println(pow(-4.0,3));
       System.out.println(pow(4.0,-2));
    }
    public static double pow(double n, int p){
        double a = 1;
        for(int i = 1;i<= Math.abs(p);i++){
            if(p>0)a*=n;
            if(p<0)a/=n;
        }
        return a;
    }
}

//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 16
/**
 * Created by Daniel on 4/24/2016.
 */
import java.util.*;
public class Exercise16 {
    public static void main(String[] args) {
        Scanner c = new Scanner(System.in);
        printPalindrome(c);
    }

    public static void printPalindrome(Scanner c) {
        System.out.print("Enter a string : ");
        String s = c.nextLine();
        String b = "";
        for (int i = s.length() - 1; i >= 0; i--) {
            b += s.charAt(i);
        }
        if (s.equalsIgnoreCase(b)) System.out.printf("%s backwards is %s, %s is a palindrome", s, b, s);
        else System.out.printf("%s backwards is %s, %s is not palindrome", s, b, s);
    }
}
//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 18
/**
 * Created by Daniel on 4/24/2016.
 */
public class Exercise18 {
    public static void main(String[] args) {
        //example calls
        System.out.println(wordCount("hello"));
        System.out.println(wordCount("how are you?"));
        System.out.println(wordCount("  this  string  has  wide  spaces  "));
        System.out.println(wordCount("  "));
    }

    public static int wordCount(String s) {
        boolean lastSpace = true;
        boolean Space = false;
        int count = 0;
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == ' ') Space = true;
            if (!Space && lastSpace) count++;
            lastSpace = Space;
            Space = false;
        }
        return count;
    }

}
//-------------------------------------------------------------------------------------------------------------------------------------
// Exercise 20
/**
 * Created by Daniel on 4/24/2016.
 */
public class Exercise20 {
    public static void main(String[] args) {
        //println statements to test numUnique
        System.out.println(numUnique(18, 3, 4));
        System.out.println(numUnique(6, 7, 6));
        System.out.println(numUnique(5, 5, 5));
    }
    public static int numUnique(int n1, int n2, int n3) {
        int u = 3;
        if (n1 == n2 && n1 == n3) u = 1;
        else if (n1 == n2 || n1 == n3 || n2 == n3) u = 2;
        return u;
    }
}