import java.util.Scanner;
public class array1 {
public static void main(String [] args){
int table[][] = new int[5][5];
Scanner scan = new Scanner(System.in);
for(int i =0; i < 5; i++){
for(int j =0; j < 5; j++){
System.out.println("Write a value for row " +i + " column " +j);
int n = scan.nextInt();
table[i][j] = n;
}
}
for(int i =0; i < 5; i++){
for(int j =0; j < 5; j++){
System.out.print(table[i][j] + "\t");
}
System.out.println();
}
int sum = 0;
boolean prime = true;
for(int i =0; i < 5; i++){
for(int j =0; j < 5; j++){
for(int e = 2; e < table[i][j]; e++ ){
if(table[i][j] % e == 0){
prime = false;
}
}
if(prime == true){
sum += table[i][j];
}
else{}
}
}
System.out.println();
System.out.println("Sum of all prime numbers in this array is " +sum);
}
}
Well, as the title itself says uhmm The program is supposed to sum up all the prime numbers in the user defined Array table but it's just summing up the first row. i checked up all the brackets, nothing helps. Any help would be appreciated! Thank you!
You should reset prime for each iteration:
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 5; j++) {
for (int e = 2; e < table[i][j]; e++) {
if (table[i][j] % e == 0) {
prime = false;
}
}
if (prime == true) {
sum += table[i][j];
} else {
}
prime = true;
}
}
Related
How to flip this triangle?
So i was making aritmethic sequance triangle. It was upside down.
How do I turn it 180 degree?
for example:
1=1
1+2=3
1+2+3=6
etc...
my code:
package javaapplication4;
public class NewClass5 {
public static void main(String[] args) {
int i=5,a;
for(int j=i; j>=1; j--) {
for(a=1; a<=i; a++)
System.out.print(a +" + ");
int n = 0;
for(a = 1; a<=i; a++) {
n = n + a;
}
System.out.print(" = "+ n);
System.out.println();
i--;
}
}
}
You can do it for any n, by getting input from the user
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
for (int i = 1; i <= n; i++) {
int add = 0;
for (int j = 1; j <= i; j++) {
System.out.print(j);
if (j == i)
System.out.print("=");
else
System.out.print("+");
add += j;
}
System.out.println(add);
}
I think you just need to change the sequence of loop from descending to ascending, rest of the things should be the same:
for (int i = 1; i <= 5; i++) {
int sum = 0;
for (int j = 1; j <= i; j++) {
System.out.print(j);
if (j == i)
System.out.print("=");
else
System.out.print("+");
sum += j;
}
System.out.println(sum);
}
When I run this, I'm able to see expected output:
src : $ java NewClass5
1=1
1+2=3
1+2+3=6
1+2+3+4=10
1+2+3+4+5=15
So for an assignment i need to make a dual-wedge figure with for loops,so far I have had no luck, can anyone help?
Here is a sample of the outcome:
*******
*** ***
** **
* *
Here's my code
int dual_wedge_length=9;
int half_length = dual_wedge_length/2;
int space=1;
int height2 = (dual_wedge_length/2) +1;
for (int line1 = 1; line1 <= dual_wedge_length; line1++)
{
System.out.print("*");
}
System.out.println();
for (int height = 1; height <= (dual_wedge_length+1)/2; height++)
{
for (int half1 = 1; half1 <= half_length; half1++)
{
System.out.print("*");
//half_length--;
space+=2;
}
for (int space_counter = 0; space_counter == space;space_counter++)
{
System.out.print(".");
}
for (int half1 = 1; half1 >= half_length; half1++)
{
System.out.print("*");
half_length--;
}
System.out.println();`
int dual_wedge_length=9;
int height2 = (dual_wedge_length+1)/2;
for(int i = 0;i < dual_wedge_length; i++)System.out.print("*");
System.out.println();
for(int i = 1; i < height2;i++){
int num = height2 - i;
for(int j = 0; j < num; j++){
System.out.print("*");
}
for(int k = 0; k < 2*i -1; k++){
System.out.print(" ");
}
for(int m = 0; m < num; m++){
System.out.print("*");
}
System.out.println();
}
I am getting an index out of bound error for this.
I set on netbeans the argument on the project and works fine.
But how can i set an argument for n within the code without going on the project properties and changing the value there?
When i try to put static int N = 4 ; i get error throughout code, can someone help me please?
package matrix;
// performing matrix multiplication parallely by using two threads
// In thread 1 we will multiply matrix a and b and store in C with range of 0 to N/2
// In thread 2 we will multiply matrix a and b and store in C with range of N/2 to N
// For our convenience I'm used 4 instead of N ( we can replace 4 with N)
public class Mymainclass implements Runnable {
static int n;
// a and b are input matrix's
static int a[][];
static int b[][];
/* we will multiply the elements in a and b matrix's
* parallely by using two threads
and will store in the c matrix sequentially.*/
static int c[][];
public Mymainclass(int n1) {
n = n1;
a = new int[n][n];
b = new int[n][n];
c = new int[n][n];
}
public void run() {
int i, j, k;
System.out.println("in thread1 class");
for (i = 0; i < this.n; i++) {
for (j = 0; j < n; j++) {
for (k = 0; k < n; k++) {
this.c[i][j] += a[i][k] * b[k][j];
}
}
}
System.out.print("\n");
System.out.println("Matrix c in thread1");
for (int a = 0; a < n; a++) {
for (int b = 0; b < n; b++) {
System.out.print(c[a][b] + " ");
}
System.out.print("\n");
}
}
public static void main(String[] args) {
String n1 = args[0];
n = Integer.parseInt(n1);
System.out.println(n);
Mymainclass th1 = new Mymainclass(n);
int z = 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
a[i][j] = z++;
}
System.out.print("\n");
}
z = 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
b[i][j] = z++;
}
System.out.print("\n");
}
System.out.println("Matrix a");
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.print(a[i][j] + " ");
}
System.out.print("\n");
}
System.out.print("\n");
System.out.println("Matrix b");
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.print(b[i][j] + " ");
}
System.out.print("\n");
}
System.out.print("\n");
Thread t = new Thread(th1);
t.start();
}
}
That is working for me:
public class Mymainclass implements Runnable {
static int n;
// a and b are input matrix's
static int a[][];
static int b[][];
/* we will multiply the elements in a and b matrix's
* parallely by using two threads
and will store in the c matrix sequentially.*/
static int c[][];
public Mymainclass(int n1) {
n = n1;
a = new int[n][n];
b = new int[n][n];
c = new int[n][n];
}
public void run() {
int i, j, k;
System.out.println("in thread1 class");
for (i = 0; i < this.n; i++) {
for (j = 0; j < n; j++) {
for (k = 0; k < n; k++) {
this.c[i][j] += a[i][k] * b[k][j];
}
}
}
System.out.print("\n");
System.out.println("Matrix c in thread1");
for (int a = 0; a < n; a++) {
for (int b = 0; b < n; b++) {
System.out.print(c[a][b] + " ");
}
System.out.print("\n");
}
}
static int N = 4 ;
public static void main(String[] args) {
Mymainclass th1 = new Mymainclass(N);
int z = 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
a[i][j] = z++;
}
System.out.print("\n");
}
z = 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
b[i][j] = z++;
}
System.out.print("\n");
}
System.out.println("Matrix a");
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.print(a[i][j] + " ");
}
System.out.print("\n");
}
System.out.print("\n");
System.out.println("Matrix b");
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.print(b[i][j] + " ");
}
System.out.print("\n");
}
System.out.print("\n");
Thread t = new Thread(th1);
t.start();
}
}
For measuring time just change code where you start thread to:
ExecutorService service = Executors.newSingleThreadExecutor();
long start = System.currentTimeMillis();
Future<?> future = service.submit(th1);
try {
future.get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
System.out.println("time: " + (System.currentTimeMillis() - start));
service.shutdown();
Where is the logic error?.. Sometimes the solution is correct and sometimes it is not. The program is suppose to calculate the row with the greatest sum and column with the greatest sum. For example:
1 1 1 1
0 0 1 0
0 0 1 0
0 0 1 0
Then the output would be:
largest row = 0
largest column = 2 //since count starts at 0
This is what I have:
import java.util.Random;
public class LargestRowAndColumn {
public static void main(String[] args) {
Random f = new Random();
int[][] m = new int[4][4];
for (int i = 0; i < m.length; i++) {
for (int j = 0;j < m[0].length; j++) {
m[i][j] = f.nextInt(2);
}
}
for (int i = 0; i < m.length; i++) {
for (int j = 0;j < m[0].length; j++) {
System.out.print(m[i][j] + " ");
}
System.out.println();
}
System.out.println("The largest row is index: " + computeRow(m));
System.out.println("The largest column is index: " + computeColumn(m));
}
public static int computeRow(int[][] m) {
int[] count = new int[m.length];
int sum;
for (int i = 0; i < 4; i++) {
sum = 0;
for (int j = 0; j < 4; j++) {
sum = sum + m[i][j];
}
count[i] = sum;
}
int maxIndex = 0;
for (int i = 0; i < i + 1; i++) {
for (int j = count.length - 1; j >= i; j--) {
if (count[i] < count[j]) {
maxIndex = j;
break;
}
}
}
return maxIndex;
}
public static int computeColumn(int[][] m) {
int[] count = new int[m.length];
int sum = 0;
for (int i = 0; i < 4; i++) {
sum = 0;
for (int j = 0; j < 4; j++) {
sum = sum + m[j][i];
}
count[i] = sum;
}
int maxIndex = 0;
for (int i = 0; i < i + 1; i++) {
for (int j = count.length - 1; j >= i; j--) {
if (count[i] < count[j]) {
maxIndex = j;
break;
}
}
}
return maxIndex;
}
}
Your maxIndex nested loop is too complex. It should be a single loop, checking the current max value seen so far with the current item in the loop. Something like this:
int maxIndex = 0;
for (int i = 1; i < count.length; i++) {
if (count[i] > count[maxIndex]) {
maxIndex = i;
}
}
return maxIndex;
Your code is correct , but
for (int i = 0; i < m.length; i++) {
for (int j = 0;j < m[0].length; j++) {
m[i][j] = f.nextInt(2);
}
}
for (int i = 0; i < m.length; i++) {
for (int j = 0;j < m[0].length; j++) {
System.out.print(m[i][j] + " ");
}
Because of the two loops:
You are creating two random 2-dimensional array instead of one.
There is one which is being printed and the other one which is not being printed but being used for index values you require so do :
System.out.print("Index" + "\t0"+"\t1"+"\t2"+"\t3" +"\n");
System.out.print("--------------------------------------------\n");
for (int i = 0; i < m.length; i++) {
System.out.print(i+ "|\t");
for (int j = 0;j < m[0].length; j++) {
m[i][j] = f.nextInt(101);
System.out.print(m[i][j] + " \t");
}
System.out.println();
}
This will also print the index, which may assist you
Why you made your job difficult. Make 2 loops, 1 for calculating the row with biggest sum, 1 for calculating the line with the bigger sum.
You don't need an int array count[i]. In your example you calculate the row with the greatest sum, you don't need to know the sum of every row after the for loop finished, so you can use a simple int bigRow.
int bigRow = 1, sumRow = 0;
// We assume that 1st row is the biggest
// Calculate the sumRow
for (int j=0;j<n;j++)
sumRow = sumRow + m[i][j] ;
// At this moment our maximum is row 1 with its sum.
// Now we compare it with the rest of the rows
// If another row is bigger, we set him as the biggest row
for ( int i=1;i<n;i++) // We start with row 2 as we calculated the 1st row
{ int auxRow = 0;
for (int j=0;j<m;j++)
{ auxRow = auxRow + m[i][j] ; }
if (auxRow > sumRow ) { auxRow=sumRow ; bigRow = i;}
}
Do the same with lines.
int bigLine = 1, sumLine = 0 ;
Let me know if you have another problem.
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
Improve this question
Everything is good, but i just cant get the addition to show up? When I run the program it is blank when it comes to the addition of the matrixes part. Thanks in advance. BtW does anyone know how I would make this display right column justified?
public static void displayMatrixes(int[][] matrix1, int[][] matrix2, int[][] resultsMatrix) {
System.out.println("This is how i want it to output");
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
System.out.print(matrix1[i][j] + " ");
}
System.out.print("+ ");
for (int j = 0; j < 3; j++) {
System.out.print(matrix2[i][j]+ " ");
}
System.out.print("= ");
for (int j = 0; j < 3; j++) {
System.out.print(resultsMatrix[i][j]+ " ");
}
System.out.println();
}
)
This is my code
import java.util.Scanner;
public class MatrixAdd
{
public static void main(String arg[])
{
Scanner input = new Scanner(System.in);
int a[][]= new int[3][3];
int b[][] = new int[3][3];
int row, column;
System.out.println("\nEnter Matrix A: \n");
for (int i = 0 ; i < 3 ; i++){
for (int j = 0; j<3 ; j++){
a[i][j] = input.nextInt();
}
}
System.out.println("\nEnter Matrix B: \n");
for (int i = 0; i < 3; i++){
for (int j = 0; j < 3; j++){
b[i][j] = input.nextInt();
}
}
System.out.println("\nMatrix A + Matrix B = Matrix C: \n");
int[][] resultingMatrix = addMatrix(a, b);
}
public static int[][] addMatrix(int[][] a, int[][] b){
int[][] result = new int[a.length][a[0].length];
for (int i = 0; i < result.length; i++) {
for (int j = 0; j < result[0].length; j++){
result[i][j]=a[i][j] + b[i][j];
}
}
for (int i = 0; i < a.length; i++) {
char plus = '+';
for (int j = 0; j < a[0].length; j++) {
System.out.print(" " + a[i][j]);
}
if (i == a.length / 2)
System.out.print(" " + plus + " ");
else {
System.out.print(" ");
}
for (int j = 0; j < b[0].length; j++) {
System.out.print(" " + b[i][j]);
}
if (i == a.length / 2)
System.out.print(" = ");
else {
System.out.print(" ");
}
for (int j = 0; j < result[0].length; j++) {
System.out.print(" " + " " + result[i][j]);
}
System.out.println();
}
return result;
}//end of add matrices
}//end of class
I doubt that the given program compiles. In this line: int[][] resultsMatrix = displayMatrixes(a, b); you are expecting an int[][], but in your method displayMatrixes you are not returning anything. You are also expecting a 3rd parameter which you are not passing.
Also, the displayMatrixes method has no return value, which since you are returning something at the end, you must have. Try it again like so:
public static void main(String arg[]) {
Scanner input = new Scanner(System.in);
int a[][] = new int[3][3];
int b[][] = new int[3][3];
int row, column;
System.out.println("\nEnter Matrix A: \n");
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
a[i][j] = input.nextInt();
}
}
System.out.println("\nEnter Matrix B: \n");
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
b[i][j] = input.nextInt();
}
}
System.out.println("\nMatrix A + Matrix B = Matrix C: \n");
displayMatrixes(a, b);
}
public static void displayMatrixes(int[][] a, int[][] b) {
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
System.out.print(a[i][j] + " ");
}
System.out.print("+ ");
for (int j = 0; j < 3; j++) {
System.out.print(b[i][j] + " ");
}
System.out.print("= ");
for (int j = 0; j < 3; j++) {
System.out.print((a[i][j] + b[i][j]) + " ");
}
System.out.println();
}
}
}
printf with The "%3d" specifier means a minimum width of three spaces, which, by default, will be right-justified.
for your right alignment question you can at http://alvinalexander.com/programming/printf-format-cheat-sheet