Pyramid pattern based on NUMBER OF STARS

[dio123321]

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

I have an idea how to do it based on numer of rows, but i dont know how to do it when I can only input number of stars.

[Ganado]

http://www.cplusplus.com/doc/tutorial/control/
https://www.learncpp.com/cpp-tutorial/for-statements/

Outer for loop goes from i = 1 to n
Inner for loop goes from j = 0 to i

Show us an attempt of you trying it yourself.

_____

Edit: I misread the problem. Having the total number of stars as input doesn't make much sense. Show us what the output should look like for, say, n = 7.
Should it look like

*
**
***
*

?

[lastchance]

Why don't you just keep writing out stars in a pyramid until you reach the requisite number of stars?

BTW, note that most numbers aren't pyramid numbers n(n+1)/2. What numbers of stars are you allowing and what do you intend with incomplete final rows?

[dio123321]

Yeah i know that for some numbers it doesnt make sense, but if i had to take a guess:
For 7* it'd be:
*
**
***
*

etc.

[dio123321]

I was told many times to input number of stars instead of rows. Even though it doesnt make sense for some numbers.

[jonnin]

and they did not say what to do when it does not make sense?
simple things, do what you can (as above, stop when hit # of stars) or drop the last row (don't use all the stars asked for is ok??) or... you can do something fancy, like find the # of rows you can do correctly, figure out how many you have left over, and insert the row that holds that many a second time.
eg for 7, 6 makes 3 rows, 1 left over, so you get
*
*
**
***

or for 9, you have 3 left over:
*
**
***
***
****

or, you can add 1 to various rows to eat the left overs... (your choice where to stick the extras)
*
**
****
for 7^^ or 9:
**
***
****

[Ganado]

You still will have a nested loop, but the inner loop will be a for loop, and the outer loop can just be a while (true) loop.

The inner for loop goes from [0, row) (row initially set to 1). Each outer loop, you increment row, and print a newline.

Also keep a "total_stars_printed" variable that you increment each time you print a star, inside each inner for loop. Also inside each inner for loop iteration, check if total_stars_printed == n. If it does, return 0; from main.

You could also do it mathematically like jonnin is saying, but a while loop works too.

[againtry]

Show the 'extras' as a separate symbol eg '-' instead of '*'

[lastchance]

#include <iostream>
#include <string>
#include <cmath>
using namespace std;

int main()
{
   int stars;
   cout << "How many stars? ";   cin >> stars;
   int rows = 0.5 * ( -1 + sqrt( 1 + 8.0 * stars ) );
   int full = rows * ( rows + 1 ) / 2;
   int remainder = stars - full;
   for ( int r = 1; r <= rows; r++ ) cout << string( r, '*' ) << '\n';
   if ( remainder ) cout << string( remainder, '*' ) + string( rows + 1 - remainder, '-' ) << '\n';
}

How many stars? 10
*
**
***
****

How many stars? 12
*
**
***
****
**---

[againtry]

Automated/annotated along the same lines

#include <iostream>
#include <string>

int main()
{
    std::string output;
    int row{0};
    int remainder{0};
    
    for( int no_stars = 1; no_stars < 20; no_stars++)
    {
        output.clear();
        row = 0;
        remainder = 0;
        
        for(int i = 0; i * (i + 1)/2 <= no_stars; i++)
        {
            output += std::string(i, '*') + '\n';
            remainder = no_stars - row * (row+1)/2;
            row++;
        }
        
        if(remainder != 0)
            output += std::string(remainder, '-') + '\n';
        
        std::cout
        << "No. of stars: " << no_stars << " No. rows: " << row - 1
        << " Remainder: " << remainder
        << output << '\n';
    }
    
    return 0;
}

No. of stars: 1 No. rows: 1 Remainder: 0
*

No. of stars: 2 No. rows: 1 Remainder: 1
*
-

No. of stars: 3 No. rows: 2 Remainder: 0
*
**

No. of stars: 4 No. rows: 2 Remainder: 1
*
**
-

No. of stars: 5 No. rows: 2 Remainder: 2
*
**
--

No. of stars: 6 No. rows: 3 Remainder: 0
*
**
***

No. of stars: 7 No. rows: 3 Remainder: 1
*
**
***
-

No. of stars: 8 No. rows: 3 Remainder: 2
*
**
***
--

No. of stars: 9 No. rows: 3 Remainder: 3
*
**
***
---

No. of stars: 10 No. rows: 4 Remainder: 0
*
**
***
****

No. of stars: 11 No. rows: 4 Remainder: 1
*
**
***
****
-

No. of stars: 12 No. rows: 4 Remainder: 2
*
**
***
****
--

No. of stars: 13 No. rows: 4 Remainder: 3
*
**
***
****
---

No. of stars: 14 No. rows: 4 Remainder: 4
*
**
***
****
----

No. of stars: 15 No. rows: 5 Remainder: 0
*
**
***
****
*****

No. of stars: 16 No. rows: 5 Remainder: 1
*
**
***
****
*****
-

No. of stars: 17 No. rows: 5 Remainder: 2
*
**
***
****
*****
--

No. of stars: 18 No. rows: 5 Remainder: 3
*
**
***
****
*****
---

No. of stars: 19 No. rows: 5 Remainder: 4
*
**
***
****
*****
----

Program ended with exit code: 0

[lastchance]

#include <iostream>
using namespace std;

int main()
{
   int stars;
   cout << "How many stars? ";   cin >> stars;
   for ( int i = 1, j = 1; stars--; j++ )
   {
      cout << '*';
      if ( j == i )
      {
         j = 0;
         i++;
         cout << '\n';
      }
   }
}

[dio123321]

Thank you guys very much! It helped me a lot.
Also is there anyway to print this pyramid reverse?

[lastchance]

dio123321 wrote:

print this pyramid reverse?

What is that supposed to mean?