Get Longest Run Index (FR)

public int getLongestRunIndex(int []values){ int maxRunStart = -1, maxRunLength = 1; int runStart = 0, runLength = 1; for(int i = 1; i <= values.length; i++) { if(i < values.length && values[i] == values[i-1]) {

runLength++; } else { if(runLength > maxRunLength) { maxRunStart = runStart; maxRunLength = runLength; } runStart = i; runLength = 1; } } return maxRunStart; }

2D Arrays

• Two-Dimensional Arrays A two-dimensional array is a table/matrix -- with rows and columns -- where each row is an array, and there are several rows in a table.e.g. a two-dimensional array of 3 rows and 4 columns

Declare a 2D array

int [][] table = new int [3][4];

0 1 2 3 +----+----+----+----+ 0 | 12 | 48 | 69 | 7 | +----+----+----+----+ 1 | 5 | 16 | 27 | 30 | +----+----+----+----+ 2 | 51 | 3 | 72 | 9 |

+----+----+----+----+

Create 2D Array

To create a two-dimensional array, you specify the number of rows (first) and columns (second). int[][] iMat = new int[3][4]; // integer matrix of 3 rows, 4 columns

double[][] dMat = new double[5][3]; // double matrix of 5 rows, 3 columns

char[][] cMat = new char[3][3]; // char matrix -- 3 rows, 3 columns

Direct Initialization

To give initial values for the elements in a two-dimensional array, you can of course set up a loop.Another way is to provide the initial values directly in declaration.

int[][] iMat = { {12, 48, 69, 7} , {5, 16, 27, 30}, {51, 3, 72, 9} };

Access an element in 2D Array• Each row is an individual array • Column index starts at 0

To access an element in a two-dimensional array, you specify the row index (first) and column index (second). System.out.println(iMat[0][2]); // prints an element at row 0, column 2 (69 in the example above) iMat[2][2] = 5; // assign 5 to row 2, column 1

0 1 2 3 +----+----+----+----+ 0 | 12 | 48 | 69 | 7 | +----+----+----+----+ 1 | 5 | 16 | 27 | | +----+----+----+----+ 2 | 51 | 3 | | +----+----+----+----+

Length 2D array

• Lengths of a Two-dimensional Array. Arrays can contain different number of column elements at each row.

0 1 2 3 +----+----+----+----+0 | 12 | 48 | 69 | 7 | +----+----+----+----+1 | 5 | 16 | 27 | | +----+----+----+----+2 | 51 | 3 | | +----+----+----+----+

LENGTH OF ROW AND COLUMN The Row length (number of rows in the array) is found by using length. int numRow = mat.length; Array to the side has 3 rows The Column Length is different for each row so you must access the row first then the column length. int columnLength = mat[0].length // equal 4 int columnLength = mat[1].length // equal 3

Traversing Over a 2D Array with for loop

Then we can utilize those two lengths to traverse over a two-dimensional array -- also by using a nested loop. Two for loops: First specify the row to loop through and then the column. Use Variables row and col to represent the row and column. int row, col; for (row = 0; row < matrix.length; row++) { for (col = 0; col < matrix[row].length; col++) System.out.print[matrix[row][col] + “ “ ); } System.out.println(); }

int[][] iMat = { {12, 48, 69, 7} , {5, 16, 27, 30}, {51, 3, 72, 9} };

0 1 2 3 +----+----+----+----+ 0 | 12 | 48 | 69 | 7 | +----+----+----+----+ 1 | 5 | 16 | 27 | | +----+----+----+----+ 2 | 51 | 3 | | +----+----+----+----+

For Wednesday

• Finish the 2 worksheets on arrays • Look over notes • Write the algorithms for the program