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.
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++) {
for the given input I need to print the pattern. For example for input = 6 I have to print:
MMMMMMSDDDDDD
MMMMMSSSDDDDD
MMMMSSSSSDDDD
MMMSSSSSSSDDD
MMSSSSSSSSSDD
MSSSSSSSSSSSD
CSSSSSSSSSSSK
CCSSSSSSSSSKK
CCCSSSSSSSKKK
CCCCSSSSSKKKK
CCCCCSSSKKKKK
CCCCCCSKKKKKK
I have tried but couldn't go further than this could anyone help
public class tgk {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int size = sc.nextInt();
int half = ((2*size)+1)/2;
for (int i = 0; i < size ; i++)
{
for (int j = size; j > i; j--)
{
System.out.print("M");
}
for (int k = half+1 ; k > half - i; k--)
{
System.out.print("S");
}
System.out.println();
}
for(int i = size; i > 0; i--)
{
for (int j = size; j >= i; j--) {
System.out.print("C");
}
for (int k = 0; k < (i * 2 - 1); k++) {
System.out.print("S");
}
System.out.println();
}
}
}
if input = 3 it should be
MMMSDDD
MMSSSDD
MSSSSSD
CSSSSSK
CCSSSKK
CCCSKKK
You can use two sets of for loops to print each half of the pattern. Assuming input variable holds the size of the problem
int input = 3;
for (int i = 0; i < input; i++) {
for (int j = 0; j < input - i; j++) {
System.out.print('M');
}
for (int j = 0; j < 2 * i + 1; j++) {
System.out.print('S');
}
for (int j = 0; j < input - i; j++) {
System.out.print('D');
}
System.out.println();
}
for (int i = input - 1; i >= 0; i--) {
for (int j = 0; j < input - i; j++) {
System.out.print('C');
}
for (int j = 0; j < 2 * i + 1; j++) {
System.out.print('S');
}
for (int j = 0; j < input - i; j++) {
System.out.print('K');
}
System.out.println();
}
will print for input = 3:
MMMSDDD
MMSSSDD
MSSSSSD
CSSSSSK
CCSSSKK
CCCSKKK
and for input = 6:
MMMMMMSDDDDDD
MMMMMSSSDDDDD
MMMMSSSSSDDDD
MMMSSSSSSSDDD
MMSSSSSSSSSDD
MSSSSSSSSSSSD
CSSSSSSSSSSSK
CCSSSSSSSSSKK
CCCSSSSSSSKKK
CCCCSSSSSKKKK
CCCCCSSSKKKKK
CCCCCCSKKKKKK
I don't know why, but I really wanted it to work with only one set of for-loops:
int number = 8;
for (int i = 0; i < number * 2; i++) {
for (int j = 0; j < (number * 2) + 1; j++) {
System.out.print(
i < number && j+i < number ? 'M' :
i < number && j-i > number ? 'D' :
i < number ? 'S' :
i >= number && i-j >= number ? 'C' :
i >= number && j+i >= number*3 ? 'K' :
'S'
);
}
System.out.println();
}
So for 8 (like in the code) it prints:
MMMMMMMMSDDDDDDDD
MMMMMMMSSSDDDDDDD
MMMMMMSSSSSDDDDDD
MMMMMSSSSSSSDDDDD
MMMMSSSSSSSSSDDDD
MMMSSSSSSSSSSSDDD
MMSSSSSSSSSSSSSDD
MSSSSSSSSSSSSSSSD
CSSSSSSSSSSSSSSSK
CCSSSSSSSSSSSSSKK
CCCSSSSSSSSSSSKKK
CCCCSSSSSSSSSKKKK
CCCCCSSSSSSSKKKKK
CCCCCCSSSSSKKKKKK
CCCCCCCSSSKKKKKKK
CCCCCCCCSKKKKKKKK
...or for 3:
MMMSDDD
MMSSSDD
MSSSSSD
CSSSSSK
CCSSSKK
CCCSKKK
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
}
}
}
So the first switch definitely occurs between the lowest value 3, and 5, but it doesn't keep going after that. This makes me think there is something wrong with one of the for loops?
public class SelectionSort
{
public static void main (String[] args)
{
int [] list;
list = new int[5];
list[0] = 4;
list[1] = 5;
list[2] = 12;
list[3] = 9;
list[4] = 3;
for (int i = 0; i < list.length-1; ++i) {
int index = i;
for (int j = 1; j < list.length; ++j) {
if (list[j] < list[index]) {
int temp = list[j];
list[j] = list[index];
list[index] = temp;
}
}
}
for (int k = 0; k < list.length; ++k) {
System.out.print(list[k] + ", ");
}
}
}
Short versión:
for (int i = 0; i < list.length-1; i++)
for (int j = i+1; j < list.length; j++)
if (list[j] < list[i]) {
int temp = list[j];
list[j] = list[i];
list[i] = temp;
}
for (int k = 0; k < list.length; k++) {
System.out.print(list[k] + ", ");
}
after if (list[j] < list[index]) {, you have to update index if boolean statement gets satisfied so you need to index = j and do the swap after
see follwing :
public class MySelectionSort {
public static int[] doSelectionSort(int[] arr){
for (int i = 0; i < arr.length - 1; i++)
{
int index = i;
for (int j = i + 1; j < arr.length; j++)
if (arr[j] < arr[index])
index = j;
int smallerNumber = arr[index];
arr[index] = arr[i];
arr[i] = smallerNumber;
}
return arr;
}
for (int i = 0; i < list.length; ++i) {
int index = i;
for (int j = i + 1; j < list.length; ++j) {
if (list[j] < list[index]) {
index = j; }}
if (index != i) {
int temp = list[i];
list[i] = list[index];
list[index] = i; }}
To cut down on the number of swaps, the loop on j should only be looking the best item to swap with item i. There should be at most one swap for each value of i. (That's what makes it a Selection sort. If you do multiple swaps for each i, you might as well be doing Bubble Sort.
But that's for efficiency. The reason your code isn't working is that you start the loop on j at j = 1 instead of j = i + 1.
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];
}