assignment6-part2

// Assignment 6 cont'd
// performs all tasks listed in Assign6

import java.util.Random;
import java.util.Scanner;
public class Assign6contd
{
 // declare instance variables
 int rows = 3, columns = 4; 
 
 // declare arrays
 int[ ] List1 = new int[12];
 int[ ] List2 = new int[12];
 int[ ][ ] List3 = new int[12][12];
 int[ ] List4 = new int[12];
 
 Scanner kb = new Scanner(System.in);
 
 // implement constructor
 public Program6contd()
 {
   this.List1 = List1;
   this.List2 = List2;
   this.List3 = List3;
   this.List4 = List4;
 }
 
 // #1 - read twelve integers and store them in a 1D array, List1. Print the Array
 public void num1()
 {
  List1 = new int[12]; 
  System.out.println("Enter 12 integer values:");
  for(int i=0; i < 12; i++)
  {
   List1[i] = kb.nextInt();   
  }
  
  System.out.println("\nList1: ");
  print1DArray(List1);
 }
 
 // #2 - Store List1 in List2
 //    - Reverse the content of array List2
 //    - Multiply each element of List1 by List2 and store them in List2
 //    - Print List 2
 public void num2()
 {
  List2 = new int[12]; 
  
  for(int i = 12 -1, j=0; i >= 0 && j < 12; i--, j++)  //  two diff arrays need diff pointers 
  {
   List2[j] = List1[i];
  }
  
  for(int i=0; i < 12; i++)
  {
   List2[i] = List2[i] * List1[i];
  }
  
  System.out.println("\nList2: ");
  print1DArray(List2);
 }
 
 // #3 - delete the third element of the array List1. Print the array
 public void num3()
 {
  for(int i =2; i < 12 - 1; i++)
  {
   List1[i] = List1[i + 1]; // deletion line
  }
  
  System.out.println("\nList1: ");
  print1DArray(List1);
 }
 
 // #4 - insert the number 22 in the array, List1, at position n. Print the array
 public void num4()
 {
  int n = generateRandomPosition(List1); // ???????
  
  for(int i = 12 - 1; i>n; i--) // decrementing = i>n, i-- 
    // incrementing = i<n, i++
  {
   List1[i] = List1[i - 1];
  }
  
  List1[n] = 22;
  
  System.out.println("\nList1: ");
  print1DArray(List1);
 } 
 
 // #5 - Store the elements of the array List1 as a 2D array, List3, with 3 rows and 4 columns
 //    - Print the array
 //    - Calculate the sum of each row and print it
 //    - Save the sum of each row in an array, List4
 public void num5()
 {
  List3 = new int[rows][columns];
  int k = 0; 
  
  for(int i =0; i < rows; i++)
  {
   for(int j=0; j < columns; j++)
   {
    List3[i][j] = List1[k];  
    k++;
   }
  }
  
  System.out.println("\nList3:");
  print2DArray(List3);
  
  List4 = new int[rows];
  
  for(int i=0; i <rows; i++)
  {
   int sum = 0;
   for(int j=0; j < columns; j++)
   {
    sum += List3[i][j];
   }
   
   System.out.println("Sum of row #" + (i + 1) + ":  " + sum);
   List4[i] = sum;
  }
 }
 
 // #6 - sort the array List4 in an increasing order, using the selection sort
 //    - print the sorted array
 public void num6()
 {
  for(int i=0; i < rows - 1; i++)
  {
   int min = i; // points to beginning of array but also keeps 
   for(int j = i + 1; j<rows; j++) // j always has to be the next number up from i! i+1
   {
    if(List4[min] > List4[j]) // if greater, min = j
    {
     min = j; // j is the pointer to the index, index is in this case needs to be the min because we need to remember the min
    }
   }

   if(i != min)
   {
     // SWAP LOOP
    int temp = List4[i]; // temp is where min gets swapped to
    List4[i] = List4[min];
    List4[min] = temp;
   }
  }
  
  System.out.println("\nList4: ");
  print1DArray(List4);
 }
 
 // #7 - Search the array List4 to find the key entered by the user
 //    - print an appropriate message if the key is not in the array
 //    - otherwise print the position where the key is found
 public void num7()
 {
  System.out.println("\nEnter key number: ");
  int key = kb.nextInt();
  
  boolean found = false;
  int index =0; // point to 0th first, index is whatever we are pointing to, like a reference 
  
  while(index < rows && !found) // not found
  {
   if(List4[index] == key)
    found = true;
   else
    index++; // go to next number
  }
  
  if(found)
   System.out.println(key + " is found at position " + index);
  else
   System.out.println(key + " is not found");
 }
 
 // method to print 1D array
 public void print1DArray(int[ ] list)
 {
  for(int i=0; i<list.length; i++)
  {
   System.out.print(list[i] + " ");
  }
  System.out.println();
 }
 
 // method to print 2D array
 public void print2DArray(int[ ][ ] list)
 {
  for(int i=0; i < list.length; i++)
  {
   for(int j=0; j < list[i].length; j++)
   {
    System.out.print(list[i][j] + " ");
   }
   System.out.println();
  }
  System.out.println();
 }
 
 // EXTRA - write a method to generate a random number for the postion n for #4
 public int generateRandomPosition(int[ ] List1)
 {
  Random rand = new Random();
  
  int randomIndex = rand.nextInt(List1.length);
  
  return randomIndex;
 }
}