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public class MainExercises public class MainExercises
{ {
/*
you should create a triangle with "*" and return a two-dimensional array of characters based on that
the triangle's area is empty, which means some characters should be " "
example 1, input = 3:
*
**
***
example 2, input = 5:
*
**
* *
* *
*****
the output has to be a two-dimensional array of characters, so don't just print the triangle!
*/
public char[][] generateTriangle(int n) { public char[][] generateTriangle(int n) {
// todo char[][] result = new char[n][n];
return null;
for (int i = 0; i < n; i++)
{
if (i == n-1)
{
for (int j = 0; j <= i; j++)
{
result[i][j] = '*';
}
}
else
{
result[i][0] = '*';
result[i][i] = '*';
}
}
return result;
} }
/*
SPIRAL TRAVERSAL OF A RECTANGULAR MATRIX
Given a rectangular matrix (2D array) of integers, this method traverses
it in a spiral order (clockwise from outside to inside) and returns
the elements as a 1D array.
EXAMPLE:
Input matrix:
1 2 3
4 5 6
7 8 9
Spiral order: start at top-left (1), go right →, then down ↓,
then left ←, then up ↑, then repeat inward.
Result: {1, 2, 3, 6, 9, 8, 7, 4, 5}
so you should walk in that matrix in a curl and then add the numbers in order you've seen them in a 1D array
RECTANGULAR MATRIX ASSUMPTION:
This method assumes the input matrix is RECTANGULAR (all rows have
the same number of columns). In Java, we can verify this because
2D arrays might be jagged (rows of different lengths).
IMPORTANT: In Java, we do NOT need to pass rows and cols!
The 2D array 'matrix' knows its own dimensions:
- Number of rows: matrix.length
- Number of columns: matrix[0].length (if rectangular)
*/
public int[] spiralTraversal(int[][] matrix) { public int[] spiralTraversal(int[][] matrix) {
// todo int rows = matrix.length, cols = matrix[0].length;
return null; int elementCount = rows * cols, curElement = 0;
int[] result = new int[elementCount];
for (int leyer = 0; curElement < elementCount; leyer++) {
int curi = leyer, maxi = rows - 1 - leyer;
int curj = leyer, maxj = cols - 1 - leyer;
for (;curj < maxj && curElement < elementCount; curj++, curElement++)
{
result[curElement] = matrix[curi][curj];
}
for (;curi < maxi && curElement < elementCount; curi++, curElement++)
{
result[curElement] = matrix[curi][curj];
}
for (;curj > leyer && curElement < elementCount; curj--, curElement++)
{
result[curElement] = matrix[curi][curj];
}
for (;curi > leyer && curElement < elementCount; curi--, curElement++)
{
result[curElement] = matrix[curi][curj];
}
if (curi == maxi || curj == maxj) {
if (curi == maxi && curj == maxj) result[curElement] = matrix[curi][curj];
break;
}
}
return result;
} }
/* /*