Asterisk Pyramid in C [closed]

问题

Exercise: make a program that reads a natural number n and draws a pyramid of asterisks. Model for n = 5:

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

Code:

int main ()
{
    int n, i, j=1, aux1, aux2;
    int spaces=1;
    scanf ("%d", &n);

    for (i=0; i<n; i++)
    {
        spaces += 1;
    }
    printf ("\n");
    for (i=0; i<n; i++)
    {
        aux1 = j;
        aux2 = spaces;

        while (aux2 >= 1)
        {
            printf (" ");
            aux2--;
        }

        while (aux1 >= 1)
        {
            printf ("*");
            aux1--;
        }

        j += 2;
        spaces--;

        printf ("\n");
    }

    return 0;
}

My code is receiving "Presentation Error" from online judge because the last asterisks of every line have a space after. Any tips on how to fix it?

回答1:

Your code has spaces at the start of each line, not the end.

Here is the simplest way I can think of to go about solving that problem:

#include <stdio.h>
#include <stdlib.h>


int main(void)
{
    int i, j, height;

    scanf("%d", &height);

    for (i = 0; i < height; i++) {
        for (j = 0; j < height - i - 1; j++)
            putchar(' ');

        for (; j < height + i; j++)
            putchar('*');

        putchar('\n');
    }

    return EXIT_SUCCESS;
}

回答2:

I'm pretty sure it's not including a space after the asterisks, and it's easy enough to see this for yourself. Near the bottom where you included the newline after the stars, I added an endmarker (|) just so we can see: is there a space?

I don't see one.

#include <stdio.h>

int main ()
{
    int n;
    scanf ("%d", &n);

    int spaces_before_stars = n - 1;

    printf ("\n");

    int i, nstars;

    for (i = 0, nstars = 1; i<n; i++)
    {
        int aux1 = nstars;
        int aux2 = spaces_before_stars;

        while (aux2-- > 0)
            printf (" ");

        while (aux1-- > 0)
            printf("*");

        nstars += 2; 

        spaces_before_stars--;

        printf ("|\n");    // the "|" marks the end of the line, remove for final
    }

    return 0;
}

However your version of the code had spaces at the start of each line, which is probably what the presentation code is unhappy with.

Refactoring the code a bit with better variable names makes it easier to follow - you should see no extra leading spaces and no trailing spaces.

回答3:

Given n>0, this should do the trick, assuming alternating blank lines is desired and a trailing extraneous new line allowed.

char *ast = malloc(n * 2);
if (ast == NULL)
   return(1);
memset(ast, '*', n*2);
ast[(n*2)-1] = 0;
for (i=1; i<=n; i++) {
   int spaces = n - i;
   printf("%*s%.*s\n\n", spaces, "", (i*2)-1, ast);
}
free(ast);
return (0);

来源：https://stackoverflow.com/questions/59709181/asterisk-pyramid-in-c

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loops

for-loop