6.14. Coding Practice

Write a program that prints out a 5x5 triangle using asterisks. An example is shown below. Your code should use while loops.

*
**
***
****
*****

#include <iostream> using namespace std; int main() { // Write your implementation here. }

Below is one way to implement the program. We use nested loops similar to the last version of the printMultTable function to print out the triangular shape.

#include <iostream> using namespace std; int main() { int row = 0; while (row < 5) { int col = 0; while (col <= row) { cout << "*"; col++; } cout << endl; row++; } }

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Selecting from: cp_6_AC_2q, cp_6_AC_2q_pp

Write a function called printPyramid that prints out an nx``n`` pyramid using asterisks. An example is shown below with n equal to 5. Your code should use while loops.

    *
   ***
  *****
 *******
*********

#include <iostream> using namespace std; void printPyramid (int n) { // Write your implementation here. } int main() { printPyramid (5); }

Below is one way to implement the program. We use multiple while loops to print out spaces and asterisks. The outer loop creates the number of rows, and within the outer loop, the two inner loops print out the correct number of spaces and asterisks.

#include <iostream> using namespace std; void printPyramid(int n) { int space, numAsterisks; int count = 1; while (count <= n) { space = n - count; while (space > 0) { cout << " "; space--; } numAsterisks = 2 * count - 1; while (numAsterisks > 0) { cout << "*"; numAsterisks--; } cout << endl; count++; } } int main() { printPyramid (5); }

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Selecting from: cp_6_AC_4q, cp_6_AC_4q_pp

A common coding interview question that’s also a popular children’s game used to teach division is FizzBuzz. Write a program that uses a while loop and prints the numbers 1 through 100, but every multiple of 3 is replaced with the word “Fizz,” every multiple of 5 is replaced with the word “Buzz,” and every multiple of both 3 and 5 is replaced with “FizzBuzz.” Your output should be the following:

1
2
Fizz
4
Buzz
...
14
FizzBuzz
16
...
98
Fizz
Buzz

#include <iostream> using namespace std; int main() { // Write your implementation here. }

Below is one way to implement the “FizzBuzz” program. We use conditionals with modulus operators in a while loop to categorize every number and print the correct output. Feel free to search up on the FizzBuzz coding interview problem if you are interested in other ways to code this program!

#include <iostream> using namespace std; int main() { int n = 1; while (n <= 100) { if (n % 3 == 0 && n % 5 == 0) { cout << "FizzBuzz" << endl; } else if (n % 3 == 0) { cout << "Fizz" << endl; } else if (n % 5 == 0) { cout << "Buzz" << endl; } else { cout << n << endl; } n++; } }

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Selecting from: cp_6_AC_6q, cp_6_AC_6q_pp

A number is a prime number if its only factors are 1 and itself. Write the function isPrime, which takes an int num as a parameters. isPrime is a boolean function that returns true if num is a prime number and returns false otherwise. Run and test your code!

#include <iostream> using namespace std; bool isPrime (int num) { // Write your implementation here. } ==== #define CATCH_CONFIG_MAIN #include <catch.hpp> TEST_CASE("isPrime function") { REQUIRE(isPrime (1) == 0); REQUIRE(isPrime (13) == 1); REQUIRE(isPrime (24) == 0); } TEST_CASE("isPrime for 0") { REQUIRE(isPrime (0) == 0); }

Below is one way to implement the isPrime function. First, we check to see if num is less than or equal to 1, and return false if that is the case. Next, we use a while loop to continuously check if a factor n divides num evenly. If it does, we return false. If no value of n divides num evenly, then we return true. Notice the while loop only goes up to num / 2 because if 2 doesn’t divide evenly, then there isn’t a smaller factor.

#include <iostream> using namespace std; bool isPrime (int num) { if (num <= 1) { return false; } int n = 2; while (n < num / 2) { if (num % n == 0) { return false; } n++; } return true; } ==== #define CATCH_CONFIG_MAIN #include <catch.hpp> TEST_CASE("isPrime function") { REQUIRE(isPrime (1) == 0); REQUIRE(isPrime (13) == 1); REQUIRE(isPrime (24) == 0); } TEST_CASE("isPrime for 0") { REQUIRE(isPrime (0) == 0); }

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Selecting from: cp_6_AC_8q, cp_6_AC_8q_pp

The Fibonacci sequence is a sequence of numbers such that each successive number is the sum of the two previous numbers. This sequence is as follows: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, and so on. Write a program that prints the first 20 Fibonacci numbers.

#include <iostream> using namespace std; int main() { // Write your implementation here. }

Below is one way to implement the program. First, we check to see if num is less than or equal to 1, and return false if that is the case. Next, we use a while loop to continuously check if a factor n divides num evenly. If it does, we return false. If no value of n divides num evenly, then we return true. Notice the while loop only goes up to num / 2 because if 2 doesn’t divide evenly, then there isn’t a smaller factor.

#include <iostream> using namespace std; int main() { int first = 0; int second = 1; int third; int n = 2; cout << first << " " << second << " "; while (n < 20) { third = first + second; cout << third << " "; first = second; second = third; n++; } }

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Selecting from: cp_6_AC_10q, cp_6_AC_10q_pp

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