Comp Sci Unit 3 #7

The following grid contains a robot represented as a triangle, which is initially in the bottom-left square of the grid and facing the top of the grid. The robot can move into a white or a gray square but cannot move into a black region.

The following code segment implements an algorithm that moves the robot from its initial position to the gray square and facing the top of the grid.

When the robot reaches the gray square, it turns around and faces the bottom of the grid. Which of the following changes, if any, should be made to the code segment to move the robot back to its original position in the bottom-left square of the grid and facing toward the bottom of the grid?

• Interchange the ROTATE_RIGHT and the ROTATE_LEFT blocks.

• Replace ROTATE_RIGHT with ROTATE_LEFT.

• Replace ROTATE_LEFT with ROTATE_RIGHT.

• No change is needed; the algorithm is correct as is.

The grid below contains a robot represented as a triangle, initially facing up. The robot can move into a white or gray square but cannot move into a black region.

The code segment below uses the procedure GoalReached, which evaluates to True if the robot is in the gray square and evaluates to otherwise.

Repeated Until (GoalReached () )

{

<Missing Code>

}

Which of the following replacements for Missing Code can be used to move the robot to the gray square?

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The following question uses a robot in a grid of squares. The robot is represented by a triangle, which is initially facing right.

Consider the procedures below.

 

Which of the following code segments will move the robot to the gray square?

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The program segment below is intended to move a robot in a grid to a gray square. The program segment uses the procedure GoalReached, which evaluates to true if the robot is in the gray square and evaluates to false otherwise. The robot in each grid is represented as a triangle and is initially facing left. The robot can move into a white or gray square but cannot move into a black region.

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The question below uses a robot in a grid of squares. The robot is represented as a triangle, which is initially in the bottom right square of the grid and facing toward the top of the grid.

The following programs are each intended to move the robot to the gray square. Program II uses the procedure , which returns  if the robot is in the gray square and returns False

 otherwise.

Which of the following statements is true?

• Program I correctly moves the robot to the gray square, but program II does not.

• Program II correctly moves the robot to the gray square, but program I does not.

• Both program I and program II correctly move the robot to the gray square.

• Neither program I nor program II correctly moves the robot to the gray square.

The question below uses a robot in a grid of squares. The robot is represented as a triangle, which is initially in the center square of the grid and facing toward the top of the grid.

The following code segment is used to move the robot within the grid.

A gray square represents a possible final location of the robot after the code segment is executed. Which of the following represents all possible final locations for the robot?

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The following grid contains a robot represented as a triangle. The robot is initially facing right.

Which of the following code segments can be used to move the robot to the gray square along the path indicated by the arrows?

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The grid below contains a robot represented as a triangle, initially facing right. The robot can move into a white or gray square but cannot move into a black region.

The code segment below uses the procedure GoalReached, which evaluates to true if the robot is in the gray square and evaluates to false otherwise.

REPEAT UNTIL (GoalReached ())

{

<MISSING CODE>

}

Which of the following replacements for <MISSING CODE> can be used to move the robot to the gray square?

• REPEAT UNTIL (CAN_MOVE (forward) = false)

  {

  ROTATE_RIGHT ()

  }

  MOVE_FORWARD ()

• REPEAT UNTIL (CAN_MOVE (forward) = false)

  {

  MOVE_FORWARD ()

  }

  ROTATE_RIGHT ()

• REPEAT UNTIL (CAN_MOVE (right))

  {

  ROTATE_RIGHT ()

  }

  MOVE_FORWARD ()

• REPEAT UNTIL (CAN_MOVE (right))

  {

  MOVE_FORWARD ()

  }

  ROTATE_RIGHT ()

The question below uses a robot in a grid of squares. The robot is represented as a triangle, which is initially in the center square and facing toward the top of the grid.

The following code segment is used to move the robot in the grid.

count ← 1

REPEAT 4 TIMES

{

REPEAT count TIMES

{

MOVE_FORWARD()

}

ROTATE_LEFT()

count ← count + 1

}

Which of the following code segments will move the robot from the center square along the same path as the code segment above?

• count ← 0

  REPEAT 4 TIMES

  {

  count ← count + 1

  REPEAT count TIMES

  {

  MOVE_FORWARD()

  }

  ROTATE_LEFT()

  }

• count ← 0

  REPEAT 4 TIMES

  {

  count ← count + 1

  ROTATE_LEFT()

  REPEAT count TIMES

  {

  MOVE_FORWARD()

  }

  }

• count ← 0

  REPEAT 4 TIMES

  {

  REPEAT count TIMES

  {

  ROTATE_LEFT()

  }

  MOVE_FORWARD()

  count ← count + 1

  }

• count ← 0

  REPEAT 4 TIMES

  {

  ROTATE_LEFT()

  REPEAT count TIMES

  {

  MOVE_FORWARD()

  }

  count ← count + 1

  }

The algorithm below is used to simulate the results of flipping a coin 4 times. Consider the goal of determining whether the simulation resulted in an equal number of heads and tails.

Step 1: Initialize the variables heads_counter and flip_counter to 0.

Step 2: A variable coin_flip is randomly assigned a value of either 0 or 1. If coin_flip has the value 0, the coin flip result is heads, so heads_counter is incremented by 1.

Step 3: Increment the value of flip_counter by 1.

Step 4: Repeat steps 2 and 3 until flip_counter equals 4.

Following execution of the algorithm, which of the following expressions indicates that the simulation resulted in an equal number of heads and tails?

• coin_flip = 1

• flip_counter = 1

• flip_counter = 2

• heads_counter = 2