Collegeboard 2015 FRQ 3

Type: List/List Iteration

Question 3

class SparseArrayEntry {
    private int row;
    private int col;
    private int value;

    public SparseArrayEntry(int row, int col, int value) {
        this.row = row;
        this.col = col;
        this.value = value;
    }

    public int getRow() {
        return row;
    }

    public int getCol() {
        return col;
    }

    public int getValue() {
        return value;
    }
}

class SparseArray {
    private List<SparseArrayEntry> entries;
    private int numRows;
    private int numCols;

    public SparseArray(int numRows, int numCols) {
        this.numRows = numRows;
        this.numCols = numCols;
        entries = new ArrayList<>();
    }

    public void addEntry(int row, int col, int value) {
        entries.add(new SparseArrayEntry(row, col, value));
    }

    public int getNumRows() {
        return numRows;
    }

    public int getNumCols() {
        return numCols;
    }

    public int getValueAt(int row, int col) {
        for (SparseArrayEntry e : entries) {
            if (e.getRow() == row && e.getCol() == col) {
                return e.getValue();
            }
        }
        return 0;
    }

    // Test for printing array
    public void printSparseArray() {
        for (int i = 0; i < numRows; i++) {
            for (int j = 0; j < numCols; j++) {
                int value = getValueAt(i, j);
                System.out.print(value + " ");
            }
            System.out.println();  // Move to the next line after each row
        }
    }

    // Test
    public static void main(String[] args) {
        SparseArray sparseArray = new SparseArray(5, 5); 
        sparseArray.addEntry(1, 4, 4); 
        sparseArray.addEntry(2, 0, 1); 
        sparseArray.addEntry(3, 1, -9);
        sparseArray.addEntry(1, 1, 5);

        sparseArray.printSparseArray();

        System.out.println();

        //Test with Row 2 Column 5
        System.out.println(sparseArray.getValueAt(1, 4)); 

        //Test with Row 3 Column 1
        System.out.println(sparseArray.getValueAt(2, 0)); 

        //Test with Row 5 Column 5
        System.out.println(sparseArray.getValueAt(4, 4)); 
    }
}

SparseArray.main(null);

0 0 0 0 0 
0 5 0 0 4 
1 0 0 0 0 
0 -9 0 0 0 
0 0 0 0 0 

4
1
0

class SparseArrayEntry {
    private int row;
    private int col;
    private int value;

    public SparseArrayEntry(int row, int col, int value) {
        this.row = row;
        this.col = col;
        this.value = value;
    }

    public int getRow() {
        return row;
    }

    public int getCol() {
        return col;
    }

    public int getValue() {
        return value;
    }
}

class SparseArray {
    private List<SparseArrayEntry> entries;
    private int numRows;
    private int numCols;

    public SparseArray(int numRows, int numCols) {
        this.numRows = numRows;
        this.numCols = numCols;
        entries = new ArrayList<>();
    }

    public void addEntry(int row, int col, int value) {
        entries.add(new SparseArrayEntry(row, col, value));
    }

    public int getNumRows() {
        return numRows;
    }

    public int getNumCols() {
        return numCols;
    }

    public int getValueAt(int row, int col) {
        for (SparseArrayEntry e : entries) {
            if (e.getRow() == row && e.getCol() == col) {
                return e.getValue();
            }
        }
        return 0;
    }

    // Test for printing array
    public void printSparseArray() {
        for (int i = 0; i < numRows; i++) {
            for (int j = 0; j < numCols; j++) {
                int value = getValueAt(i, j);
                System.out.print(value + " ");
            }
            System.out.println();  // Move to the next line after each row
        }
    }

    public void removeColumn(int col) {
        int i = 0;
        while (i < entries.size()){
            SparseArrayEntry e = entries.get(i);
            if (e.getCol() == col){
                entries.remove(i);
            }
            else if (e.getCol() > col){
                entries.set(i, new SparseArrayEntry(e.getRow(), e.getCol()-1, e.getValue()));
                i++;
            }
            else{
                i++;
            }
        }
        numCols--;
    }

    public static void main(String[] args) {
        SparseArray sparseArray = new SparseArray(5, 5); 
        sparseArray.addEntry(1, 4, 4); 
        sparseArray.addEntry(2, 0, 1); 
        sparseArray.addEntry(3, 1, -9);
        sparseArray.addEntry(1, 1, 5);

        sparseArray.printSparseArray();

        System.out.print("Value at Row 2 Column 5: "); 
        System.out.println(sparseArray.getValueAt(1, 4)); 
        System.out.print("Value at Row 3 Column 1: "); 
        System.out.println(sparseArray.getValueAt(2, 0)); 
        System.out.print("Value at Row 5 Column 5: "); 
        System.out.println(sparseArray.getValueAt(4, 4)); 

        System.out.println(); 

        sparseArray.removeColumn(1);

        sparseArray.printSparseArray();

        System.out.print("Value at Row 2 Column 5: "); 
        System.out.println(sparseArray.getValueAt(1, 4)); 
        System.out.print("Value at Row 3 Column 1: "); 
        System.out.println(sparseArray.getValueAt(2, 0)); 
        System.out.print("Value at Row 5 Column 5: "); 
        System.out.println(sparseArray.getValueAt(4, 4));
    }
}

SparseArray.main(null);

0 0 0 0 0 
0 5 0 0 4 
1 0 0 0 0 
0 -9 0 0 0 
0 0 0 0 0 
Value at Row 2 Column 5: 4
Value at Row 3 Column 1: 1
Value at Row 5 Column 5: 0

0 0 0 0 
0 0 0 4 
1 0 0 0 
0 0 0 0 
0 0 0 0 
Value at Row 2 Column 5: 0
Value at Row 3 Column 1: 1
Value at Row 5 Column 5: 0