Mario

Problem to Solve

Toward the end of World 1-1 in Nintendo’s Super Mario Bros., Mario must ascend right-aligned pyramid of bricks, as in the below.

screenshot of Mario jumping up a right-aligned pyramid

In a file called mario.c in a folder called mario-less, implement a program in C that recreates that pyramid, using hashes (#) for bricks, as in the below:

       #
      ##
     ###
    ####
   #####
  ######
 #######
########

But prompt the user for an int for the pyramid’s actual height, so that the program can also output shorter pyramids like the below:

  #
 ##
###

Re-prompt the user, again and again as needed, if their input is not greater than 0 or not an int altogether.

Hints

Recall that you can get an int from a user with get_int, which is declared in cs50.h.
Recall that you can print a string with printf, which is declared in stdio.h.

Demo

Advice

Write some code that you know will compile

Even though this program won’t do anything, it should at least compile with make!

#include <cs50.h>
#include <stdio.h>

int main(void)
{

}

Write some pseudocode before writing more code

If unsure how to solve the problem itself, break it down into smaller problems that you can probably solve first. For instance, this problem is really two problems:

Prompt the user for the pyramid’s height
Print a pyramid of that height

So write some pseudcode as comments that remind you to do just that:

#include <cs50.h>
#include <stdio.h>

int main(void)
{
    // Prompt the user for the pyramid's height

    // Print a pyramid of that height
}

Convert the pseudocode to code

First, consider how you might prompt the user for the pyramid’s height. Recall that a do while loop is helpful when you want to do something at least once, and possibly again and again, as in the below:

#include <cs50.h>
#include <stdio.h>

int main(void)
{
    // Prompt the user for the pyramid's height
    int n;
    do
    {
        n = get_int("Height: ");
    }
    while (n < 1);

    // Print a pyramid of that height
}

Second, consider how you might print a pyramid of that height, from top to bottom. Notice how the first row should have one brick, the second row should have two bricks, and so on. Odds are you’ll want a loop, as in the below, even if not (yet!) sure what to put in that loop. So add some more pseudocode as a comment for now:

#include <cs50.h>
#include <stdio.h>

int main(void)
{
    // Prompt the user for the pyramid's height
    int n;
    do
    {
        n = get_int("Height: ");
    }
    while (n < 1);

    // Print a pyramid of that height
    for (int i = 0; i < n; i++)
    {
        // Print row of bricks
    }
}

How to print that row of bricks? Well, wouldn’t it be nice if there were a function called print_row that could do just that? Let’s suppose that there is:

#include <cs50.h>
#include <stdio.h>

void print_row(int bricks);

int main(void)
{
    // Prompt the user for the pyramid's height
    int n;
    do
    {
        n = get_int("Height: ");
    }
    while (n < 1);

    // Print a pyramid of that height
    for (int i = 0; i < n; i++)
    {
        // Print row of bricks
    }
}

void print_row(int bricks)
{
    // Print row of bricks
}

We could then call that function from main, as in the below:

#include <cs50.h>
#include <stdio.h>

void print_row(int bricks);

int main(void)
{
    // Prompt the user for the pyramid's height
    int n;
    do
    {
        n = get_int("Height: ");
    }
    while (n < 1);

    // Print a pyramid of that height
    for (int i = 0; i < n; i++)
    {
        // Print row of bricks
        print_row(i + 1);
    }
}

void print_row(int bricks)
{
    // Print row of bricks
}

Why i + 1, though?

Let’s now implement print_row:

#include <cs50.h>
#include <stdio.h>

void print_row(int bricks);

int main(void)
{
    // Prompt the user for the pyramid's height
    int n;
    do
    {
        n = get_int("Height: ");
    }
    while (n < 1);

    // Print a pyramid of that height
    for (int i = 0; i < n; i++)
    {
        // Print row of bricks
        print_row(i + 1);
    }
}

void print_row(int bricks)
{
    for (int i = 0; i < bricks; i++)
    {
        printf("#");
    }
    printf("\n");
}

Why the \n at the end, though?

Unfortunately, this code prints a left-aligned pyramid, but you need a right-aligned one! Perhaps we should print some blank spaces before some of the bricks, to move them to the right? Let’s change print_row as follows so that it can print both:

#include <cs50.h>
#include <stdio.h>

void print_row(int spaces, int bricks);

int main(void)
{
    // Prompt the user for the pyramid's height
    int n;
    do
    {
        n = get_int("Height: ");
    }
    while (n < 1);

    // Print a pyramid of that height
    for (int i = 0; i < n; i++)
    {
        // Print row of bricks
    }
}

void print_row(int spaces, int bricks)
{
    // Print spaces
    
    // Print bricks
}

Some pseudocode now remains in both main and print_row, so that we leave to you!

And consider whether you could factor out some of the code in main to a get_height function, too, that returns the int you need!

Walkthrough

How to Test

Does your code work as prescribed when you input:

-1 or other negative numbers?
0?
1 or other positive numbers?
letters or words?
no input at all, when you only hit Enter?

Correctness

check50 cs50/problems/2023/spring/mario/less

Style

style50 mario.c

How to Submit

After you submit, be sure to check your autograder results. If you see SUBMISSION ERROR: missing files (0.0/1.0), it means your fil e was not named exactly as prescribed (or you uploaded it to the wrong problem).

Correctness in submissions entails everything from reading the specification, writing code that is compliant with it, and submitting files with the correct name. If you see this error, you should resubmit right away, making sure your submission is fully compliant wi th the specification. The staff will not adjust your filenames for you after the fact!

Download your mario.c file by control-clicking or right-clicking on the file in your codespace’s file browser and choosing Dow nload.
Go to CS50’s Gradescope page.
Click Problem Set 1: Mario (Less).
Drag and drop your mario.c file to the area that says Drag & Drop. Be sure it has that exact filename! If you upload a fil e with a different name, the autograder likely will fail when trying to run it. Ensuring you have uploaded files with the correct fil ename is your responsibility!
Click Upload.

You should see a message that says “Problem Set 1: Mario (Less) submitted successfully!”