public class Sort {
public static void main(String[] args) {
//fill the array with random numbers
int[] unsorted = new int[100];
for(int i = 0; i < 100; i++) {
unsorted[i] = (int) (Math.random() * 100);
}
System.out.println("Here are the unsorted numbers:");
for(int i = 0; i < 100; i++) {
System.out.print(unsorted[i] + " ");
}
System.out.println();
int[] sorted = new int[100];
for(int i = 0; i < 100; i++) {
int hi = -1;
int hiIndex = -1;
for(int j = 0; j < 100; j++) {
if(unsorted[j] > hi) {
hi = unsorted[j];
hiIndex = j;
}
}
sorted[i] = hi;
unsorted[hiIndex] = -1;
}
System.out.println("Here are the sorted numbers: ");
for(int i = 0; i < 100; i++) {
System.out.print(sorted[i] + " ");
}
System.out.println();
}
}
So this is in descending order but I want to reverse it.
I tried changing the if(unsorted[j] > hi) {
to a if(unsorted[j] < hi) {
[edit:changed greater than to less than, both were same]
Okay, you want the numbers to be in ascending order. So for descending, you assume that compared number would be -1 and all other number must be grater than this -1, now instead of -1 use the maximum value a number could be. Assign Integer.MAX_VALUE where you were assigning -1. So change your code like this:
int[] sorted = new int[100];
for(int i = 0; i < 100; i++) {
int hi = Integer.MAX_VALUE;
int hiIndex = i;
for(int j = 0; j < 100; j++) {
if(unsorted[j] < hi) {
hi = unsorted[j];
hiIndex = j;
}
}
sorted[i] = hi;
unsorted[hiIndex] = Integer.MAX_VALUE;
Related
Write a bubble sort program that prints the number of swaps made after M number of iterations (In this case, ‘M’ should be an input value).
For example, if M = 0, the bubble sort program will perform 0 swaps in 0 iterations.
In bubble sort, an iteration is defined as the total number of times the outer loop runs. Assume that:
M <= the array size and
the program sorts in descending order.
The code should ask the user to input the values for M, the array size, and finally the elements of the array. So, there will be three types of inputs —
Input 1: The value of M
Input 2: The size of the array
Input 3: The elements inside the array
Sample Input:
2
4
1
2
3
4
Sample Output:
5
Please help me in solving the Bubble Sort Problem. Here I run the program but I am getting 3 in place of 5.
here's my code :
package com.company;
import java.util.*;
class Source {
static int totalBubbleSortSwaps(int[] array, int M) {
int pass=0;
boolean isDone;
for (int k = 0; k < ( array.length-1 ); k++) {
isDone=true;
for (int j = 0; j < array.length-k-1; j++) {
if (array[j] < array[j+1])
{
//isDone=false;
int temp = array[j];
array[j] = array[j+1];
array[j+1] = temp;
pass++;
}
}
if(isDone){
break;
}
}
//for (pass =1; pass <m; ++pass){
//for (k = 0; k < size; k++)
return pass;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int m = scanner.nextInt();
int size = scanner.nextInt();
int array[] = new int[size];
for (int i = 0; i < size; i++) {
array[i] = scanner.nextInt();
}
System.out.println(totalBubbleSortSwaps(array, m));
}
}
count the number of swaps made after M runs of the outer loop.
A couple observations.
you are sorting the values in descending order. Is that correct?
you need to only count the swaps while m > 0.
after each outer loop, decrement m by 1 (for each iteration of the outer loop).
you are not setting your isDone flag.
Here is what I came up with. I changed pass to swaps.
public class BubbleSort {
static int totalBubbleSortSwaps(int[] array, int m) {
int swaps = 0;
boolean isDone;
for (int k = 0; k < (array.length - 1); k++) {
isDone = true;
for (int j = 0; j < array.length - k - 1; j++) {
if (array[j] > array[j + 1]) { // <----- changed to > from <
isDone=false;
int temp = array[j];
array[j] = array[j + 1];
array[j + 1] = temp;
if (m > 0) {
swaps++; // <---- update swap count
}
}
}
if (isDone) {
break;
}
m--; <---- decrement m
}
return swaps;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int m = scanner.nextInt();
int size = scanner.nextInt();
int array[] = new int[size];
for (int i = 0; i < size; i++) {
array[i] = scanner.nextInt();
}
System.out.println(totalBubbleSortSwaps(array, m));
}
}
}
import java.util.Scanner;
class Source {
static int totalBubbleSortSwaps(int[] array, int m) {
int swaps = 0;
for (int k = 0; k < m; k++) {
for (int j = 0; j < array.length - k - 1; j++) {
if (array[j] < array[j + 1]) {
int temp = array[j];
array[j] = array[j + 1];
array[j + 1] = temp;
swaps++;
}
}
}
return swaps;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int m = scanner.nextInt();
int size = scanner.nextInt();
int array[] = new int[size];
for (int i = 0; i < size; i++) {
array[i] = scanner.nextInt();
}
System.out.println(totalBubbleSortSwaps(array, m));
}
}
The below code will give you the number of swaps done in bubble sort (descending order) when "M" iterations are done in the outer loop:
import java.util.*;
public class BubbleSortSwaps {
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
int M = scanner.nextInt();
int size = scanner.nextInt();
int array[] = new int[size];
for (int i = 0; i < size; i++) {
array[i] = scanner.nextInt();
}
System.out.println(totalBubbleSortSwaps(array, M));
}
}
static int totalBubbleSortSwaps(int[] array, int M) {
int size = array.length;
int totalSwaps = 0;
for (int i = 0; i < M; i++) {
Boolean swap = false;
for (int j = 1; j < size - i; j++) {
int swapTemp = 0;
if (array[j - 1] < array[j]) {
swapTemp = array[j - 1];
array[j - 1] = array[j];
array[j] = swapTemp;
swap = true;
totalSwaps++;
}
}
if (!swap)
break;
}
return totalSwaps;
}
}
I have a java code to read the length of an integer array, output the range, length of the gap, and any distinct elements inside. Additionally, it will output the numbers again with none repeated.
I would like to shorten the length of my main method.
My code produces the correct output, it is just very lengthy. Additionally, is there a way I can edit this main method to where it won't require a drastic change to my other methods? Thank you so much!
package ArrayPrograms;
import java.util.Scanner;
public class WIP{
static int LargestGap(int [] a, int n)
{
int diff = Math.abs(a[1] - a[0]);
for(int i = 1; i < a.length-1; i++)
if(Math.abs(a[i+1]-a[i]) > diff)
diff = Math.abs(a[i+1] - a[i]);
return diff;
}
int range(int a[], int n)
{
int max1 = Integer.MIN_VALUE;
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
if (Math.abs(a[i] - a[j]) > max1)
{
max1 = Math.abs(a[i] - a[j]);
}
}
}
return max1;
}
int numberOfDistinctElement(int a[], int n)
{
int num = 1;
for (int i = 1; i < n; i++)
{
int j = 0;
for (j = 0; j < i; j++)
if (a[i] == a[j])
break;
if (i == j)
num++;
}
return num;
}
int[] distinctElements(int a[], int n,int numberofDistinct)
{
int index = 0;
int[] distinct= new int[numberofDistinct];
for (int i = 0; i < n; i++)
{
int flag = 0;
for (int j = 0; j < i; j++){
if (a[i] == a[j]){
flag = 1;
break;
}
}
if (flag == 0){
distinct[index] = a[i];
index++;
}
}
return distinct;
}
***public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int num;
WIP obj=new WIP();
System.out.print("Enter the length of the array:");
num = in.nextInt();
int array[] = new int[num];
System.out.print("Enter the elements of the array: ");
for(int i = 0; i < num; i++)
{
array[i] = in.nextInt();
}
System.out.println("The largest gap in the array is "+WIP.LargestGap(array,num)+".");
System.out.println("The range of the array is "+obj.range(array,num)+".");
int numberofDistinct=obj.numberOfDistinctElement(array,num);
System.out.println("The number of distinct elements is "+numberofDistinct+".");
int[] distinctArray=obj.distinctElements(array,num,numberofDistinct);
System.out.print("The array of distinct elements is [");
for (int i = 0; i < distinctArray.length; i++)
if(i== distinctArray.length-1)
{
System.out.print(distinctArray[i]+"]");
}
else {
System.out.print( distinctArray[i]+ ",");
}
in.close();
}
}***
Sure thing. Here you go:
package arrayprograms;
import java.util.Scanner;
public class WIP{
static int LargestGap(int [] a, int n)
{
int diff = Math.abs(a[1] - a[0]);
for(int i = 1; i < a.length-1; i++)
if(Math.abs(a[i+1]-a[i]) > diff)
diff = Math.abs(a[i+1] - a[i]);
return diff;
}
int range(int a[], int n)
{
int max1 = Integer.MIN_VALUE;
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
if (Math.abs(a[i] - a[j]) > max1)
{
max1 = Math.abs(a[i] - a[j]);
}
}
}
return max1;
}
int numberOfDistinctElement(int a[], int n)
{
int num = 1;
for (int i = 1; i < n; i++)
{
int j = 0;
for (j = 0; j < i; j++)
if (a[i] == a[j])
break;
if (i == j)
num++;
}
return num;
}
int[] distinctElements(int a[], int n,int numberofDistinct)
{
int index = 0;
int[] distinct= new int[numberofDistinct];
for (int i = 0; i < n; i++)
{
int flag = 0;
for (int j = 0; j < i; j++){
if (a[i] == a[j]){
flag = 1;
break;
}
}
if (flag == 0){
distinct[index] = a[i];
index++;
}
}
return distinct;
}
static void showResults(int[] array, int num, WIP obj){
System.out.println("The largest gap in the array is "+WIP.LargestGap(array,num)+".");
System.out.println("The range of the array is "+obj.range(array,num)+".");
int numberofDistinct=obj.numberOfDistinctElement(array,num);
System.out.println("The number of distinct elements is "+numberofDistinct+".");
int[] distinctArray=obj.distinctElements(array,num,numberofDistinct);
System.out.print("The array of distinct elements is [");
for (int i = 0; i < distinctArray.length; i++)
if(i== distinctArray.length-1)
{
System.out.print(distinctArray[i]+"]");
}
else {
System.out.print( distinctArray[i]+ ",");
}
}
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int num;
WIP obj=new WIP();
System.out.print("Enter the length of the array:");
num = in.nextInt();
int array[] = new int[num];
System.out.print("Enter the elements of the array: ");
for(int i = 0; i < num; i++)
{
array[i] = in.nextInt();
}
in.close();
showResults(array, num, obj );
}
}
There's not a whole lot you can do, like most of the comments say, but you can remove and edit some of the braces around that aren't necessary for the bodies. Here is a rough draft of it. The only things you could change besides that is to store all of the WIP.tests in variables in one code block and then print them all out in another code block; which would improve readability.
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
WIP obj = new WIP();
System.out.print("Enter the length of the array:");
int num = in.nextInt();
int array[] = new int[num] ;
System.out.print("Enter the elements of the array: ");
for(int i = 0; i < num; i++)
array[i] = in.nextInt();
System.out.println("The largest gap in the array is " + WIP.LargestGap(array,num) + ".");
System.out.println("The range of the array is " + obj.range(array,num) + ".");
int numberofDistinct = obj.numberOfDistinctElement( array, num );
System.out.println("The number of distinct elements is "+numberofDistinct+".");
int[] distinctArray = obj.distinctElements(array,num,numberofDistinct);
System.out.print("The array of distinct elements is [");
for (int i = 0; i < distinctArray.length; i++)
if(i== distinctArray.length-1)
System.out.print(distinctArray[i]+"]");
else
System.out.print( distinctArray[i]+ ",");
in.close();
}
I need the maximum elements position if there is more than one maximum element then the first one is to be printed.
My code prints the position of the maximum element but not the first one.
I don't understand why the last iteration is not working as I intend it to.
Please solve it using only Java.
import java.util.Scanner;
class Main {
public static void main(String[] args) {
// put your code here
Scanner sc = new Scanner(System.in);
// define lengths
int n = sc.nextInt();
int m = sc.nextInt();
// add length to matrix
int[][] matrix = new int[n][m];
// insert elements
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
matrix[i][j] = sc.nextInt();
}
}
// define max
int max = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (matrix[i][j] > max) {
max = matrix[i][j];
}
}
// System.out.print(i + " " + j);
}
// System.out.print(max + " ");
// print index of highest element
// int pos1 = 0;
// int pos2 = 0;
for (int i = 0; i < n; ++i) {
for (int j = 0; j < m; ++j) {
if (matrix[i][j] == max) {
System.out.print(i + " " + j);
break;
}
// pos2 += 1;
break;
}
// pos1 += 1;
// break;
}
}
}
There is no need to go through the matrix twice. When you are searching for the max, store also the coordinates of the matrix where that max was found. A code example:
import java.util.Scanner;
class Main {
public static void main(String[] args) {
// put your code here
Scanner sc = new Scanner(System.in);
// define lengths
int n = sc.nextInt();
int m = sc.nextInt();
// add length to matrix
int[][] matrix = new int[n][m];
// insert elements
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
matrix[i][j] = sc.nextInt();
}
}
// define max
int max = Integer.MIN_VALUE, row=0, col=0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (matrix[i][j] > max) {
max = matrix[i][j];
row=i;
col=j;
}
}
}
System.out.print("max: "+max + " is at: ");
System.out.print(col + " " + row); //indexes starting from zero
}
}
Create a new variable to hold the position of the max value and set it in the current loop
int max = matrix[0][0];
int[] maxPos = new int[2];
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
if (matrix[i][j] > max) {
max = matrix[i][j];
maxPos[0] = i;
maxPos[1] = j;
}
}
}
and then remove the rest of the code and print the result
System.out.printf("Max is %d and is found at [%d, %d]\n", max, maxPos[0], maxPos[1]);
Trying to write a method that swaps the rows of a 2D array in order of increasing row sum.
For example, if I have the following 2d array:
int [][] array = {4,5,6},{3,4,5},{2,3,4};
I would want it to output an array as so:
{2 3 4}, {3 4 5}, {4 5 6}
Methodology:
a.) take the sums of each row and make a 1D array of the sums
b.) do a bubble sort on rowSum array
c.) swap the rows of the original array based on the bubble sort swaps made
d.) then print the newly row sorted array.
Here's my code so far:
public void sortedArrayByRowTot() {
int [][] tempArray2 = new int [salaryArray.length [salaryArray[0].length];
for (int i = 0; i < tempArray2.length; i++) {
for (int j = 0; j < tempArray2[i].length; j++) {
tempArray2[i][j] = salaryArray[i][j];
}
}
int [] rowSums = new int [tempArray2.length];
int sum = 0;
for (int i = 0; i < tempArray2.length; i++) {
for (int j = 0; j < tempArray2[i].length; j++) {
sum += tempArray2[i][j];
}
rowSums[i] = sum;
sum = 0;
}
int temp;
int i = -1;
for(int j = rowSums.length; j > 0; j--){
boolean isSwap = false;
for (i = 1; i < j; i++) {
if(rowSums[i-1] > rowSums[i]) {
temp = rowSums[i-1];
rowSums[i-1] = rowSums[i];
rowSums[i] = temp;
isSwap = true;
}
}
if(!isSwap){
break;
}
}
for (int k = 0; k < tempArray2.length; k++) {
temp = tempArray2[i-1][k];
tempArray2[i-1][k] = tempArray2[i][k];
tempArray2[i][k] = temp;
}
for (int b = 0; b < tempArray2.length; b++) {
for (int c = 0; c < tempArray2[b].length; c++) {
System.out.print(tempArray2[b][c] + " ");
}
}
}
}
Not sure if I am doing part c of my methodology correctly?
It keeps saying "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2"
As #shmosel said, you can do it like this:
public static void sortedArrayByRowTot() {
int [][] array = {{4,5,6},{3,4,5},{2,3,4}};
Arrays.sort(array, Comparator.comparingInt(a -> IntStream.of(a).sum()));
}
I was able to solve my question. Thanks.
public void sortedArrayByRowTot() {
//Creates tempArray2 to copy salaryArray into
int [][] tempArray2 = new int [salaryArray.length][salaryArray[0].length];
//Copies salaryArray into tempArray2
for (int i = 0; i < salaryArray.length; i++) {
for (int j = 0; j < salaryArray[i].length; j++) {
tempArray2[i][j] = salaryArray[i][j];
}
}
//Creates rowSum array to store sum of each row
int [] rowSums = new int [tempArray2.length];
for (int i = 0; i < tempArray2.length; i++) {
for (int j = 0; j < tempArray2[0].length; j++) {
rowSums[i] += tempArray2[i][j];
}
}
//Modified Bubble Sort of rowSum array (highest to lowest values)
int temp;
int i = 0;
for(int j = rowSums.length; j > 0; j--){
boolean isSwap = false;
for (i = 1; i < j; i++) {
if(rowSums[i-1] < rowSums[i]) {
temp = rowSums[i-1];
rowSums[i-1] = rowSums[i];
rowSums[i] = temp;
isSwap = true;
//swaps rows in corresponding tempArray2
int [] temp2 = tempArray2[i-1];
tempArray2[i-1] = tempArray2[i];
tempArray2[i] = temp2;
}
}
if(!isSwap){
break;
}
}
//Prints sorted array
System.out.println("Sorted array: ");
for (i = 0; i < tempArray2.length; i++) {
for (int j = 0; j < tempArray2[i].length; j++) {
System.out.print("$"+ tempArray2[i][j] + " ");
}
System.out.println();
}
}
You may try this way. That I have solved.
public class Solution{
public static void sortedArrayByRowTot() {
int [][] salaryArray = { {4,5,6},{3,4,5},{2,3,4} };
int [][] tempArray2 = new int [salaryArray.length][salaryArray[0].length];
for (int i = 0; i < salaryArray.length; i++) {
for (int j = 0; j < salaryArray[i].length; j++) {
tempArray2[i][j] = salaryArray[i][j];
}
}
// Buble Sort to store rowSums
int [] rowSums = new int [tempArray2.length];
for (int i = 0; i < tempArray2.length; i++) {
for (int j = 0; j < tempArray2[0].length; j++) {
rowSums[i] += tempArray2[i][j];
}
}
//Buble Sort by Rows Sum (Lowest Value to Highest)
int temp;
int i = 0;
for(int j = rowSums.length; j > 0; j--){
boolean isSwap = false;
for (i = 1; i < j; i++) {
if(rowSums[i-1] > rowSums[i]) {
temp = rowSums[i-1];
rowSums[i-1] = rowSums[i];
rowSums[i] = temp;
isSwap = true;
//swaps rows in corresponding tempArray2
int [] temp2 = tempArray2[i-1];
tempArray2[i-1] = tempArray2[i];
tempArray2[i] = temp2;
}
}
if(!isSwap){
break;
}
}
/** No Need.
for (int k = 0; k < tempArray2.length; k++) {
temp = tempArray2[i-1][k];
tempArray2[i-1][k] = tempArray2[i][k];
tempArray2[i][k] = temp;
}
*/
for (int b = 0; b < tempArray2.length; b++) {
for (int c = 0; c < tempArray2[b].length; c++) {
System.out.print(tempArray2[b][c] + " ");
}
}
}
public static void main(String[] args) {
sortedArrayByRowTot();
}
}
I am trying to sort an array of random numbers without using the arrays.sort. I have the code, but it doesn't work. not sure where is the error. Any kind of help is appreciated.
import java.util.*;
public class Sort
{
public static void main(String args[])
{
Scanner in = new Scanner(System.in);
System.out.print("How many numbers do you want? ");
int howMany = in.nextInt();
int [] myArray = getRandomArray(howMany);
}
/* public static int bsearch(int[] arr, int key)
{
}*/
public static int[] getRandomArray(int howMany) {
int[] returnMe = new int[howMany]; // Assume size >= 0
Random rand = new Random();
for (int i = 0; i < howMany ; i++)
returnMe[i] = rand.nextInt(Integer.MAX_VALUE) + 1;
//System.out.print(returnMe[i] + " ");
for (int i = 1; i <= (howMany - 1); i++)
{
for (int j = 0; j < howMany - i -1; j++)
{
int tmp = 0;
if (returnMe[j] > returnMe[j+1])
{
tmp = returnMe[j];
returnMe[j] = returnMe[j + 1];
returnMe[j + 1] = tmp;
}
}
}
for ( int i = 0; i < howMany; i++)
System.out.println(returnMe[i] + " ");
return returnMe;
}
}
Your line
for (int j = 0; j < howMany - i -1; j++)
should be
for (int j = 0; j <= howMany - i -1; j++)
or alternatively, remove the "-1" and keep "<". Otherwise, you will ignore the last number in the array. Everything else looks fine to me.