Unit 3 - Boolean Expressions and if Statements

• 3.1 -
• 3.2 -
• 3.3 -
• 3.4 -
• 3.5 -
• 3.6 -
• 3.7 -
• Coding Challenge 1 -
• Coding Challenge 3 -
• Possible CollegeBoard Test Question Topics:
• Scavenger Hunt (done on paper)
• HW: 2019 FRQ 1:
  • a)
  • b)
  • Quizziz: Completed

3.1 -

• Boolean Expressions: represent logic and tell whether something is true or false
• Operators used to create Booleans
• "==" (same value/equals to)
• "!=" (checks for inequality)
• "<" (less than)
• "<=" (less than or equal to)
• ">" (greater than)
• ">=" (greater than or equal to)

3.2 -

• Conditional Statements - perform computations depending on whether a Boolean condition evaluates to true or false
• If Statements - if statement occurs if a block of code is run only if the condition is true

3.3 -

• If-Else Statements - statement to run a block of code among more than one alternative

3.4 -

• Else-if Statements - statement to run a condition if the original condition was false

3.5 -

• Nested if statements - If-statements within if-statements
  • Note - If the outer if-statement evaluates to false, the inner if-statements are not evaluated.
• Logical operators - Used to combine Boolean expressions
  • && - and
  • || - or
  • ! - not
• Short-circuited evaluation: The result of a compound Boolean expression can be determined just by looking at a few expressions.

3.6 -

• De Morgan's laws: Help simplify Boolean expressions
  • !(a&&b) = (!a || !b)
  • !(a || b) = (!a && !b)

3.7 -

• Use '==' to see if two object references are aliases for the same object or to see if an object is null
• Use '.equals()' to see if the attributes of two objects are the same

Coding Challenge 1 -

• my answer: 1 4 5 6 7 8 9

Coding Challenge 3 -

• my answer: true false true true

Possible CollegeBoard Test Question Topics:

• equals vs == operator (The == operator will only check if pointing at the same objects)
• if only using 1 line of code, {} is not needed between if-statements
• conditionals must have if or else-if to latch onto
• conditionals and control structures can be nested

Scavenger Hunt (done on paper)

• my answer: Mr M's Desk

HW: 2019 FRQ 1:

public class FrogSimulation
{
/** Distance, in inches, from the starting position to the goal. */
private int goalDistance;
/** Maximum number of hops allowed to reach the goal. */
 private int maxHops;
/** Constructs a FrogSimulation where dist is the distance, in inches, from the starting
* position to the goal, and numHops is the maximum number of hops allowed to reach the goal.
* Precondition: dist > 0; numHops > 0
*/
 public FrogSimulation(int dist, int numHops)
{
goalDistance = dist;
maxHops = numHops;
}
/** Returns an integer representing the distance, in inches, to be moved when the frog hops.
 */
private int hopDistance()
{ /* implementation not shown */ }
/** Simulates a frog attempting to reach the goal as described in part (a).
* Returns true if the frog successfully reached or passed the goal during the simulation;
* false otherwise.
*/
 public boolean simulate()
{ /* to be implemented in part (a) */ }
 /** Runs num simulations and returns the proportion of simulations in which the frog
* successfully reached or passed the goal.
* Precondition: num > 0
*/
 public double runSimulations(int num)
{ /* to be implemented in part (b) */ }
}

a)

/** Simulates a frog attempting to reach the goal as described in part (a).
* Returns true if the frog successfully reached or passed the goal during the simulation;
* false otherwise.
*/
public boolean simulate() {
    int position = 0; // frog starts at 0
    for (int count = 0; count < maxHops; count++) { // maxHops is the max the frog can hop, and after each hop the count goes up by one, the loop repeating until count = maxHops
        position += hopDistance();
        if (position >= goalDistance) { // if the frog goes farther than needed, return true
            return true;
        }
        else if (position < 0) { // if the frog isn't there, return false and keep going
            return false;
        }
    }
    return false; // if the hops are taken up without the goal being met, it returns false
}

b)

/** Runs num simulations and returns the proportion of simulations in which the frog
* successfully reached or passed the goal.
* Precondition: num > 0
*/
public double runSimulations(int num) { // double makes it so the value can be a decimal
    int countSuccess = 0; // starts at 0
    for (int count = 0; count < num; count++) { // checks if the simulation was successful for each time it was run
        if(simulate()) { // if it turns out true, raise the count of the number of successful runs
            countSuccess++;
        }
    }
    return (double)countSuccess / num; // divides the number of successes to the overall amount of simulations to find the final result
}

Quizziz: Completed