I'm unsure how to add the row with the exception of the first column.This is what I have so far.I'm trying to get the output to be 5=1+2+3, 7=1+2+4, 8=3+5+9 . I will put it in another array to record the difference.
public class Main {
static int[][] Array = { { 5, 1, 2, 3 }, { 7, 1, 2, 4 }, { 8,3,5,9 } };
public int[] sum(int[][] array) {
int index = 0;
int temp[] = new int[array[index].length];
for (int i = 0; i < array.length; i++) {
int sum = 0;
for (int j = 0; j < array[i].length; j++) {
sum += array[j][i];
}
temp[index] = sum;
System.out.println("Index is: " + index + " Sum is: " + sum);
index++;
}
return temp;
}
public static void main(String[] args) {
new Main().sum(Array);
}
}
Change
for (int j = 0; j < array[i].length; j++) {
sum += array[j][i];
}
to
for (int j = 1; j < array[i].length; j++) {
sum += array[i][j];
}
output:
Index is: 0 Sum is: 6
Index is: 1 Sum is: 7
Index is: 2 Sum is: 17
never check <= when i=0 just < is enough
change the this line
for (int j = 0; j < array[i].length; j++) {
sum += array[j][i];
}
to this
for (int j = 1; j < array[i].length; j++) {
sum += array[i][j];
}
Related
I am trying to figure out how to increment a pyramid based on input from the user.\
If a user enters the number 3, my program will print a pyramid of height 3, three times.\
What I would like it to do instead, is to print 3 pyramids, but the first pyramid should have a height of 1, and the second a height of 2, and the third a height of 3.
Here is my code:
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
for (int l = 0; l < n; l++) {
System.out.println("Pyramid " + n);
for (int i = 1; i <= n; i++) {
for (int j = 0; j < n - i; j++) {
System.out.print(".");
}
for (int j = 0; j < i; j++) {
System.out.print("#");
}
for (int j = 1; j < i; j++) {
System.out.print("#");
}
for (int k = 0; k < n - i; k++) {
System.out.print(".");
}
System.out.println();
}
}
You use l to keep track of the number of pyramid you're working on, so you could just use it in the loop instead of n. Note that l starts with 0, not 1, so you may want to amend the loop accordingly and run from 1 to n, not from 0 to n-1
for (int l = 1; l <= n; l++) { // Note the loop starts at 1
System.out.println("Pyramid " + l);
for (int i = 1; i <= l; i++) { // Note the usage of l instead on n
for (int j = 0; j < l - i; j++) {
System.out.print(".");
}
for (int j = 0; j < i; j++) {
System.out.print("#");
}
for (int j = 1; j < i; j++) {
System.out.print("#");
}
for (int k = 0; k < l - i; k++) { // Note the usage of l instead on n
System.out.print(".");
}
System.out.println();
}
}
All you have to change is this part of code
System.out.println("Pyramid " + (l+1));
for (int i = 1; i <= l+1; i++) {
I've this codes:
public class matrixExample {
public static void main(String[] args) {
int m[][] = new int[5][5];
int count = 1;
for (int i=0; i<m.length; i++)
for(int j=0; j<i+1; j++)
m[i][j] = count++;
for (int i=0; i<m.length; i++)
{
for (int j=0; j<m[i].length; j++)
System.out.print(m[i][j] + " ");
System.out.println();
}
}
}
And output:
How can I do as in the screenshot below?
int size = 5;
int[][] m = new int[size][size];
int count = 1;
for (int i = 0; i < size; ++i)
for (int j = size - i - 1; j < size; ++j)
m[i][j] = count++;
You may populate the matrix as suggested in saka1029's answer above and then print it using formatted output:
for (int i = 0; i < m.length; i++) {
for (int j = 0; j < m[i].length; j++) {
System.out.printf(" %2d ", m[i][j]);
}
System.out.print('\n');
}
Or, it is possible to keep "normal" matrix, and change only its output:
public static void main(String []args){
int m[][] = new int[5][5];
int count = 1;
// keeping initial array as is
for (int i=0; i<m.length; i++)
for(int j=0; j<i+1; j++)
m[i][j] = count++;
for (int i = 0; i < m.length; i++) {
StringBuilder sb = new StringBuilder();
for (int j = 0; j < m[i].length; j++) {
if (m[i][j] > 0) {
sb.append(String.format(" %2d ", m[i][j]));
} else {
sb.insert(0, String.format(" %2d ", m[i][j]));
}
}
System.out.println(sb.toString());
}
}
Output in both cases is identical:
0 0 0 0 1
0 0 0 2 3
0 0 4 5 6
0 7 8 9 10
11 12 13 14 15
I have 4x4 2D array that already has values in each index. I want to have a function that calculates the sum of a row/column of the array and store it at the first/final column and have the other indexes revert to 0.
This is what I have to render my array:
public static void print2Darray(int[][] numbers) {
for (int i = 0; i < numbers.length; i++) {
for (int j = 0; j < numbers.length; j++) {
System.out.print(numbers[i][j]);
System.out.print("\t");
}
System.out.println();
}
}
Which displays something like this:
10 15 30 40
15 5 8 2
20 2 4 2
1 4 5 0
Currently this is the function that I have:
public static void sumLeft(int[][] numbers) {
for (int i = 0; i < numbers.length; i++) {
numbers[i][0] = (numbers[i][0] + numbers[i][1] + numbers[i][2] + numbers[i][3]);
if (i == 3) {
numbers[0][1] = 0;
numbers[0][2] = 0;
numbers[0][3] = 0;
numbers[1][1] = 0;
numbers[1][2] = 0;
numbers[1][3] = 0;
numbers[2][1] = 0;
numbers[2][2] = 0;
numbers[2][3] = 0;
numbers[3][1] = 0;
numbers[3][2] = 0;
numbers[3][3] = 0;
}
}
}
Which does this:
95 0 0 0
30 0 0 0
28 0 0 0
10 0 0 0
I just want to find an algorithm that would do this without "cheating" or just hacking my way through it.
All you need to do is loop over the elements of the "row" array:
public static void sumLeft(int[][] numbers) {
for (int i = 0; i < numbers.length; i++) {
for (int j = 1; j < numbers[i].length; j++) {
numbers[i][0] += numbers[i][j];
numbers[i][j] = 0;
}
}
}
Why did not you do simple this:
for (int i = 0; i < numbers.length; i++) {
for (int j = 1; j < numbers[i].length; j++) {
numbers[i][0] += numbers[i][j];
numbers[i][j] = 0;
}
}
Use the inner loop in the reverse order as:
for (int i = 0; i < numbers.length; i++) { // for all rows
int sum = 0; // about to be sum, reset every row
for (int j = numbers[i].length -1 ; j >=0; j--) { // iterate reverse in columns
if (j == 0) {
numbers[i][j] += sum; // final sum
} else {
sum += numbers[i][j]; // keep evaluating
numbers[i][j] = 0; //reset
}
}
}
I have already done with normal jagged array, but I don't understand how to reverse it upside down. Also I have a question, how to shift the side of triangle from left side to right? Can I do this with loops or I need to write different quantity of whitespaces for every line of my array?
static int[][] triangle(int lines){
int[][] arr = new int[lines][];
for(int i = 0; i < arr.length; i++){
arr[i] = new int[i + 1];
}
int count = 0;
for(int i = 0; i < arr.length; i++){
for(int j = 0; j < arr[i].length; j++){
arr[i][j] = count++;
}
}
for(int i = 0; i < arr.length; i++){
for(int j = 0; j < arr[i].length; j++){
System.out.print(arr[i][j] + " ");
}
System.out.println();
}
return arr;
}
Some kind of result:
0
1 2
3 4 5
6 7 8 9
10 11 12 13 14
You can quickly create a reversed triangle by changing the way you initialize your arr array.
static int[][] revTriangle(int lines) {
int[][] arr = new int[lines][];
for (int i = 0; i < arr.length; i++) {
arr[i] = new int[lines - i]; // this line
}
int count = 0;
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
arr[i][j] = count++;
}
}
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
System.out.print(arr[i][j] + " ");
}
System.out.println();
}
return arr;
}
I get the following output:
0 1 2 3 4
5 6 7 8
9 10 11
12 13
14
Hope this helps!
If you need a more compact solution you can group some loops (basing on anacron answer):
static int[][] triangle( int lines, boolean straight)
{
int[][] arr = new int[lines][];
int count = 0;
for ( int i = 0; i < arr.length; i++ )
{
int start = (straight? i : lines);
int step = (straight? 1 : -i);
arr[i] = new int[start + step ];
for ( int j = 0; j < arr[i].length; j++ )
{
arr[i][j] = count++;
System.out.print( arr[i][j] + " " );
}
System.out.println();
}
return arr;
}
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.