APCS Written Test Practice Barron's 1

APCS-Test-Practice-Barron's-1.java

// 1a
public static void reverseArray(int[] arr) {
	for(int i = 0; i = arr.length / 2; i++) {
		arr[i] = arr[i] + arr[arr.length - i - 1];
		arr[arr.length - i - 1] = arr[i] - arr[arr.length - i - 1];
		arr[i] = arr[i] - arr[arr.length - i - 1];
	}
}

// 1b
public void reverseAllRows() {
	for(int[] row : mat)
		ArrayUtil.reverseArray(row);
}

// 1c
public void reverseMatrix() {
	reverseAllRows();
	for(int i = 0; i < mat.length / 2; i++) {
		int[] temp = mat[i];
		mat[i] = mat[mat.length - i - 1];
		mat[mat.length - i - 1] = temp;
	}
}

// 2a
public List<Integer> getBlankPositions() {
	List<Integer> toReturn = new List<Integer>();
	String temp = sentence;
	while(temp.indexOf(' ') != -1) {
		toReturn.add(temp.indexOf(' ');
		temp = temp.substring(temp.indexOf(' '));
	}
	return toReturn;
}

// 2b
public int countWords() {
	if(sentence.length() != 0)
		return (getBlankPositions().size() + 1);
	return 0;
}

// 2c
public String[] getWords() {
	List<Integer> blankPos = getBlankPositions();
	blankPos.add(sentence.length() + 1);
	String[] words = new String[countWords()];
	for(int i = 0; i < countWords(); i++) {
		words[i] = sentence.substring(blankPos.get(i) + 1, blankPos.get(i + 1));
	}
	return words; 
}

// 3a
public Player requestSlot(String playerName) {
	for(int i = 0; i < slots.length; i++) {
		if(slots[i] == null) {
			slots[i] = new Player(playerName, i);
			return slots[i];
		}
	}
	waitingList.add(playerName);
	return null;
}

// 3b
public Player cancelAndReassignSlot(Player p) {
	slots[p.getPlayerNumber()] = null;
	if(waitingList.size() != 0) {
		slots[p.getPlayerNumber()] = new Player(waitingList.remove(0), p.getPlayerNumber());
	}
	return slots[p.getPlayerNumber()];
}

// 4a
public void reset() {
	if(arm.isFacingRight())
		arm.changeDirection();
	while(arm.getCurrentIndex() != 0)
		arm.moveForward(1);
	// answer key has while loop replaced with arm.moveForward(arm.getCurrentIndex())
	arm.changeDirection();
}

// 4b
public int mostAcidic() {
  reset();
  int minPH = 7, minIndex = 0;
  for(int i = 0; i < solutions.size(); i++) {
    Solution s = solutions.get(i);
    if(s.getPH() < minPH) {
      minIndex = i;
      minPH = s.getPH();
    }
  }
  if(minPH == 7) {
    return -1;
  } else {
    arm.moveForward(minIndex);
    return minIndex;
  }
}

Can we have 4c please