2.9 Implementing Selection and Iteration Algorithms

1. Exam Points

• identify if an integer is or is not evenly divisible by another integer
• identify the individual digits in an integer
• determine the frequency with which a specific criterion is met
• determine a minimum or maximum value
• compute a sum or average
• Note:
  • Range of the loop control variable (1-19, 1-20, or (1,3,5,7,9))
  • How the loop control variable changes. (++, --, +=2, +=3)
  • Find a number that meets a criterion.
    • (x % 3==1) x = 3n+1
    • (x % 7==2) x = 7n+2

2. Knowledge Points

(1) Implementing Selection and Iteration Algorithms

• Constructs/structures(构造) widely used in algorithms:
  • Selection
    • if
    • if-else
    • if-else if
  • Iteration/Loop
    • while loops
    • for loops
• There are standard algorithms to:
  • 1. identify if an integer is or is not evenly divisible by another integer
    • Ex. identify a multiple of 2 and 7
      
  • 2. identify the individual digits in an integer
    • Ex. print each digit in a number reversely
      
  • 3. determine the frequency with which a specific criterion is met
    • Ex. count multiples of 6 between 1 to 30
      
  • 4. determine a minimum or maximum value
    • Ex. find the minimum among 3 numbers
      
  • 5. compute a sum or average
    • Ex. calculate the sum of numbers between 10 and 20

3. Exercises

• Practice
• Solution