Sum, Accumulators, Product and Counter. Nested loops

Содержание:

Theory
- Sum (addition)
Labs and tasks

Theory

Sum (addition)

Syntax:
The sum in Pascal is calculated by the recurrent expression:

S = S + Y
where S is the accumulated amount
Y – next summand

Labs and tasks

Sum (addition)

Lab 1:

To do: 10 numbers are given. It’s required to calculate their sum.

✍ Algorithm:

sum

sum

{0.3 points} Task 1, sum:

To do: 5 integers are entered. After entering each number, the program should print their sum.

Expected output:

'please, enter 5 numbers:'
>>> 4
entered number: 4  => sum = 4
>>> 7
entered number: 7 => sum = 11  
>>> 3
entered number: 3 => sum = 14  
... etc.

[Program name: task-01-sum.pas]

{0.3 points} Task 2, sum:

To do: 5 real numbers are entered. The program should output their sum only once, just before the end of the program.

Expected output:

entered numbers: 
>>> 4.2  >>> 7.1  >>> 3.1  >>> 2.5  >>> 8.6
sum = 25.5

[Program name: task-02-sum.pas]

{0.3 points} Task 3, sum:

To do: Count the sum of 10 numbers: 1 + 2 + 3 + … + 10. Better use for loop.

[Program name: task-03-sum.pas]

{0.3 points} Task 4, sum:

To do: Count the sum of 5 numbers: 1 + 3 + 5 + 7 + 9. Better use for loop with an arbitrary step.

Expected output:

'1 + 3 + 5 + 7 + 9 ='
25

[Program name: task-04-sum.pas]

{0.4 points} Task 5, sum:

To do: Calculate a sum of all odd integers up to 99 (1 + 3 + 5 + 7 + 9 + 11 + … + 99). Use for loop with an arbitrary step.

Expected output:

'1 + 3 + 5 + 7 + 9 + ... + 99 ='
2500

[Program name: task-05-sum.pas]

{0.4 points} Task 6, sum:

To do: Calculate a sum of all odd integers up to 99 (1 + 3 + 5 + 7 + 9 + 11 + … + 97 + 99). Use loop.

[Program name: task-06-sum.pas]

Lab 2: Sum – short solution

To do: 10 integers are given. It’s required to calculate their sum.

✍ Algorithm:

{0.3 points} Task 7, sum:

To do: 5 integers are entered. The program should output their sum only once, before the end of the program. Use short form as in the lab.

[Program name: task-07-sum.pas]

Product (multiplication)

Lab 3:

To do: 10 reals are given. It’s required to calculate their product (multiplication).

✍ Algorithm:

The product variable is initialized by 1 value before loop. Every loop iteration the product is incremented by the value of the next number.

{0.3 points} Task 1, product:

To do: 5 integers are entered. After entering each number, the program should print their product.

Expected output:

'please, enter 5 numbers:' 
>>> 4
entered number: 4  => product = 4
>>> 3
entered number: 3 => product = 12 
>>> 5
entered number: 5 => product = 60 

... etc.

[Program name: task-01-product.pas]

{0.3 points} Task 2, product:

To do: 5 real numbers are entered. The program should output their product only once, just before the end of the program:

Expected output:

entered numbers: 
>>> 4.2  >>> 7.1  >>> 3.1  >>> 2.5  >>> 8.6
product = 1987.503

[Program name: task-02-product.pas]

{0.4 points} Task 3, product:

To do: Calculate a product of 2-digit even integers in the interval [10;30] (10 * 12 * 14 * … * 28 * 30). Use for loop with an arbitrary step.

Expected output:

product = 165412864

[Program name: task-03-product.pas]

Lab 4: Product (multiplication) — short solution

To do: 10 real numbers are given. It’s required to calculate their product.

✍ Algorithm:

{0.1 points} Task 4, product:

To do: 5 real numbers are entered. The program should output their product only once, just before the end of the program:

Expected output:

entered numbers: 
>>> 4.2  >>> 7.1  >>> 3.1  >>> 2.5  >>> 8.6
product = 1987.503

[Program name: task-04-product.pas]

{0.3 points} Task 5, product:

To do: 5 integers are entered. The program should output their product only once — just before the end of the program. Use short form as in the example.

Expected output:

enter 5 integers, please:
>>>2  >>>5  >>>1  >>>7  >>>3
product is: 210

[Program name: task-05-product.pas]

Counters

Lab:

To do: n >= 0 is given. The program should ask to input n integer numbers and find a quantity of odd numbers among entered numbers.

Solution: We’re going to use an if statement in a loop.

Expected output:

how many numbers? 
>>>4
enter the numbers: 
>>>1  >>>3  >>>8  >>>7
the number of odd:  3

✍ Algorithm:

begin
  print('how many numbers?');
  var n := ReadInteger;
  print('enter the numbers:');
  var count := 0;
  loop n do
  begin
    var x := ReadInteger;
    if x mod 2 <> 0 then
      count += 1;
  end;
  print('the number of odd: ', count)
end.

{0.2 points} Task 1, counters:

To do: Ouput a sequence: 1 2 3 4 . . . 99 100. Use loop and a variable named counter:
A code snippet:

...
var counter:=0;
loop 100 do
   begin
         ...
         print(counter);
   end;

Expected output:

1 2 3 4 5 . . . 99 100

[Program name: task-01-counters.pas]

{0.3 points} Task 2, counters:

To do: Ouput a sequence: 1 2 3 4 . . . 99 100 99 . . . 3 2 1.

Note: Create two loops: the first loop should iterate through 1 2 3 4 . . . 99 100, the second loop through 99 . . . 3 2 1.

Expected output:

1 2 3 4 . . . 97 98 99 100 99 98 . . . 4 3 2 1

[Program name: task-02-counters.pas]

{0.2 points} Task 3, counters:

To do: Ten randomized integers are given. You should use for loop and variable named counter to find the quantity of positive among the numbers.

Note: You should use random function to have randomized sequence of numbers:

var genNumb: integer;
//...
genNumb:=random (a,b);

Note: you can complete the following code:

begin
  var genNumb, i: integer;
  var counter := 0;
  for i := 1 to 10 do
  begin
    genNumb := random(-5, 10);
    // to do ...
    // ...
  end;
  writeln;
  print('numbers of positive: ', counter)
end.

Expected output:

1 6 10 10 -2 1 -4 4 -4 2 
numbers of positive:  7

[Program name: task-03-counters.pas]

Several counters

Lab:

To do: Pupil has got n grades (marks) for the exams (from 2 to 5), they are given. Calculate a number of each grade (how many “2”, how many “3” …).

Solution: We will use several counters, each counter for each grade.

Expected results

how many grades? 5
enter grades, please
4
4
4
2
3
"2"= 1, "3"= 1, "4"= 3, "5"= 0

✍ Algorithm:

begin
  var n := ReadInteger('how many grades?');
  var (c2, c3, c4, c5) := (0, 0, 0, 0);
  writeln('enter grades, please');
  loop n do
  begin
    var Mark := ReadInteger;
    case Mark of
      2: c2 += 1;
      3: c3 += 1;
      4: c4 += 1;
      5: c5 += 1;
    end;
  end;
  Print($'"2"= {c2}, "3"= {c3}, "4"= {c4}, "5"= {c5}');
end.

{0.4 points} Task 4, counters:

To do: Ten randomized integers are given. Use loop and two counters to find the quantity of positive and negative among the numbers.

Note: You should use random function to have randomized sequence of numbers:

var genNumb: integer;
//...
genNumb:=random (a,b);

Expected output:

1  -5  -12   2   3   9   -1  9   5   -8   
counter positive = 6, counter negative = 4

[Program name: task-04-counters.pas]

{0.4 points} Task 5, counters:

To do: Ten randomized integers are given. Use loop and two counters to find the quantity of even and odd among the numbers.

Expected output:

1  -5  -12   2   3   9   -1  9   5   -8  
counter even = 3, counter odd = 7

[Program name: task-05-counters.pas]

Minimum and maximum value

Lab:

To do: n numbers are given (n >= 0). Find minimum value of these numbers.

✍ Algorithm:

Solution 1.

min

begin
  var n:=readinteger('enter n');
  var x := ReadReal;
  var min := x;
  loop n - 1 do
  begin
    x := ReadReal;
    if x < min then
      min := x;
  end;
  print($'min = {min}')
end.

What is not good: The first value is handled separately.

Solution 2. Let’s set the maximum value of real type (real.MaxValue) to min variable. Then, in a loop check if the first entered number is less than min. If it is, so reassign this value to min.

The idea is that after the first iteration min will be reassigned in any case because x < real.MaxValue:

begin
    var n:=readinteger('enter n');
    var x:real;
    var min := real.MaxValue;
    loop n do
    begin
      x := ReadReal;
      if x < min then
        min := x;
    end;
    print($'min = {min}')
end.

{0.2 points} Task 1, min & max:

To do: 5 numbers are entered. Output the maximum and minimum of entered numbers.

Note: complete the following code snippet:

begin
  var // ...;
  var min := integer.MaxValue;
  var max := integer.MinValue;
  loop 5 do
  begin
    // ...
  end;
  print($'min = {min}, max = {max}')
end.

Expected output:

enter 5 integers:
>>> 5  >>> 3  >>> 8  >>> 1  >>> 2  
maximum is 8, minimum is 1

[Program name: task-01-maxmin.pas]

{0.5 points} Task 2, min & max:

To do: An integer N is given and a set of N rectangles defined by their sides (pairs of numbers a and b for each rectangle). Calculate the areas (S = a * b) of all the rectangles and output minimum area of them.

Expected output:

How many rectangles?
>>> 3
Please, enter the sides of the rectangles:
>>> 2  >>> 3
area is: 6
>>> 1  >>> 5
area is: 5
>>> 4  >>> 2
area is: 8
The minimum area of all rectangles is 5

[Program name: task-02-maxmin.pas]

{0.5 points} Task 3, min & max:

To do: An integer N is given and a set of N rectangles defined by their sides (pairs of numbers a and b). Find the perimeters of all the rectangles and output maximum perimeter of them.

Expected output:

How many rectangles?
>>> 3
Please, enter the sides of the rectangles:
>>> 2  >>> 3
perimeter: 10
>>> 1  >>> 5
perimeter: 12
>>> 4  >>> 2
perimeter: 12
The maximum perimeter of all rectangles is 12

[Program name: task-03-maxmin.pas]

{0.3 points} Task 4, min & max:

To do: Find the minimum of 5 numbers and output it's sequential number (order number). To store the sequential number you must use extra variable.

Note: You should use random function to have randomized sequence of numbers:

var genNumb: integer;
//...
genNumb:=random (a,b);

Expected output:

5 generated numbers:
5   3   8   1   2 
minimum is 1, its position is 4

[Program name: task-04-maxmin.pas]

{0.5 points} Task 5, min & max:

To do: Calculate a minimum and maximum of 10 generated numbers and print the sum of their sequential number (order positions or serial numbers).

Note: You should use random function to have randomized sequence of numbers:

var genNumb: integer;
//...
genNumb:=random (a,b);

Expected output:

10 generated numbers:
2  15  3  8  1  2  9  1  7  11   
max is 15 position is 2, min is 1 position is 8, 2 + 8 = 10

[Program name: task-05-maxmin.pas]

Sums and products in the while and repeat loops

Lab:

To do: Calculate the sum of the sequence: 11 + 13 + 15 + ... + 99.

Expected results:

sum = 2475

✍ Algorythm:

While loop:

begin
  var x:=11;
  var s:=0;
  while x<=99 do
  begin
    s+=x;
    write(x);
    x+=2;
  end;
  Print($'sum = {s}');
end.

Loop:

{0.3 points} Task 1, sum and while:

To do: Calculate a sum of all odd 2-digit integers (11+ 13 + 15 + 17 + 19 + 21 + ... + 99). Make the task two times - using while and repeat loops.

Expected output:

while loop. sum = 2475 
repeat loop. sum = 2475

[Program name: task-01-sum-while.pas]

{0.3 points} Task 2, sum and while:

To do: Calculate a product of 2-digit even integers in the range [10;30] (10 * 12 * 14 * ... * 28 * 30). Make the task two times - using while and repeat loops.

Expected output:

while loop. product = 667418624  
repeat loop. product = 667418624

[Program name: task-02-sum-while.pas]

{0.3 points} Task 3, sum and while:

To do: 5 real numbers are entered. The program should output their sum only once, just before the end of the program. Make the task two times - using while and repeat loops.

Expected output:

please enter 5 numbers: 
>>> 4.2  >>> 7.1  >>> 3.1  >>> 2.5  >>> 8.6
sum = 25.5

[Program name: task-03-sum-while.pas]

{0.3 points} Task 4, sum and while:

To do: 5 numbers are entered. The program should output their product (multiplication) only once, just before the end of the program. Make the task two times - using while and repeat loops.

Expected output:

please enter 5 numbers: 
>>> 4  >>> 7  >>> 3  >>> 2  >>> 8
multiplication = 1344

[Program name: task-04-sum-while.pas]

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