ap computer science a 2021 free response questions answers code example

Example 1: 2019 ap computer science free response answers

// Part A
public ArrayList<String> getDelimitersList(String[] tokens) {
	ArrayList<String> out = new ArrayList<>();
	for (String t: tokens) {
		if (t.equals(openDel) || t.equals(closeDel))
			out.add(t); 
	}
	return out; 
}

// Part B
public boolean isBalanced(ArrayList<String> delimiters) {
	int open = 0;
	int close = 0;
	for (String d: delimiters) {
		if (d.equals(openDel))
			open++;
		else if (d.equals(closeDel))
			close++;
		
		if (close > open)
			return false;
	}
	return open == close; 
}

Example 2: 2019 ap computer science free response answers

// Part A
public LightBoard(int numRows, int numCols) {
	lights = new boolean[numRows][numCols];
	for (int r=0; r<numRows; r++)
		for (int c=0; c<numCols; c++)
			lights[r][c] = Math.random() < 0.4; 
}

// Part B
public boolean evaluateLight(int row, int col) {
	int onInCol = 0;
	for (int r=0; r<lights.length; r++)
		if (lights[r][col])
			onInCol++;
	if (lights[row][col] && onInCol % 2 == 0)
		return false;
	else if (!lights[row][col] && onInCol % 3 == 0)
		return true;
	return lights[row][col];
}