Star printing in C in a difficult way

Question

I started practicing some C and found this nice exercise when I need to print a triangle using input. for input 6 he will print

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

Now, looking at this, I thought it wasn’t such a difficult task. So I decided to try and write it using recursion, without loops and only 2 variables. the function should look like this:

void PrintTriangle(int iMainNumber, int iCurrNumber)
{
   //Logic goes here
}

After a few hours, I realized that this is much more complicated than I thought, since I need to pass enough information so that the function can “remember” how many triangles should print.

So, now I decided to ask you if this is possible.

(remember, no loops, no other functions, only recursion).

EDIT: , - . , , .

void PrintTriangle(int iMainNumber, int iCurrNumber)
{
    if (iMainNumber == 0)
    {
        printf("\r\n");
    }
    else if (iMainNumber == iCurrNumber)
    {
        printf("\r\n");
        PrintTriangle(iMainNumber - 1, 0);
    }
    else
    {
        printf("%s", MYCHAR);
        PrintTriangle(iMainNumber, iCurrNumber + 1);
    }
}

, , , , , iMainNumber iCurrNumber , .

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, .

Answer 1

:

void PrintTriangle(int size, int indent)
{
    switch(size) {
    case 0:
        if (indent > 1) PrintTriangle(size, indent-1);
        putchar('*');
        break;
    case 1:
        PrintTriangle(size-1, indent+1);
        putchar('\n');
        break;
    default:
        PrintTriangle(1, indent);
        PrintTriangle(size-1, indent+1);
        PrintTriangle(1, indent);
        break; }
}

int main()
{
    PrintTriangle(6, 0);
    return 0;
}

. , .

size - , indent - . size==0 indent ( )

- , :

void PrintTriangle(int size, int indent)
{
    if (size <= 0) {
        if (indent > 1) PrintTriangle(size, indent-1);
        putchar('*');
    } else {
        if (size > 1) PrintTriangle(1, indent);
        PrintTriangle(size-1, indent+1);
        if (size > 1) PrintTriangle(1, indent);
        else putchar('\n'); }
}

Answer 2

, , . , , , .

, , -. size, . , lineNumber 1 size*2-1 columnNumber 1 size. :

columnsForLine = lineNumber <= size ? lineNumber : size*2 - lineNumber

:

int lineNumber = 1;
int columnNumber = 1;
int size = 6;
while (lineNumber <= size*2-1) {        
    printf("*");
    int columnsForLine = lineNumber <= size ? lineNumber : size*2 - lineNumber;
    if (columnNumber == columnsForLine) {
        printf("\n");
        columnNumber = 1;
        lineNumber += 1; 
    }
    else {
        columnNumber += 1;
    }
}

. ? , , :

void recstars(int size, int lineNumber, int columnNumber) {
    if (!(lineNumber <= size*2 - 1)) {
        return;
    }
    printf("*");
    int columnsForLine = lineNumber <= size ? lineNumber : size*2 - lineNumber;
    if (columnNumber == columnsForLine) {
        printf("\n");
        recstars(size, lineNumber + 1, 1);
    }
    else {
        recstars(size, lineNumber, columnNumber + 1);
    }
}
recstars(6, 1, 1);

voila. , . 13.

, , -. , , , .

---

, 2 , , , ... 3 , . .

void recstars(int state) {
    int size = state / 10000;
    int lineNumber = (state - size*10000) / 100;
    int columnNumber = state - size*10000 - lineNumber*100;
    if (!(lineNumber <= size*2 - 1)) {
        return;
    }
    printf("*");
    int columnsForLine = lineNumber <= size ? lineNumber : size*2 - lineNumber;
    if (columnNumber == columnsForLine) {
        printf("\n");
        recstars(size*10000 + (lineNumber+1)*100 + 1);
    }
    else {
        recstars(size*10000 + lineNumber*100 + (columnNumber+1));
    }
}
recstars(6*10000 + 1*100 + 1);

, . , ?

- , 2 ints . ?

Answer 3

, OP

void PrintTriangle(int iMainNumber, int iCurrNumber) {
  if (iMainNumber < 0) { // Row (use negative iMainNumber)
    printf("%c", '*');
    PrintTriangle(iMainNumber + 1, 0);
    if (iMainNumber == -1)
      printf("\n");
  } else if (iMainNumber > 0) { 
    if (iCurrNumber < iMainNumber) { // Preceding short lines
      if (iCurrNumber > 1)
        PrintTriangle(iMainNumber, iCurrNumber - 1);
      PrintTriangle(-iCurrNumber, 0);
    } else if (iCurrNumber == iMainNumber) { 
      PrintTriangle(iMainNumber, iCurrNumber - 1);  // left
      PrintTriangle(iMainNumber, iCurrNumber + 1);  // Right
    } else {                         // Subsequent short lines
      if ((iCurrNumber - iMainNumber) < iMainNumber)
        PrintTriangle(iMainNumber, iCurrNumber + 1);
      PrintTriangle(-(iCurrNumber - iMainNumber), 0);
    }
  }
}

int main() {
  PrintTriangle(3,3);
  PrintTriangle(6,6);
  return 0;
  }

Answer 4

, , , , .

. , , . . , , .

, . , . , . , .

void _print_stars(int height, int total, int current)
{
    int stars = current <= height ? current : 2 * height - current;

    for (int i = 0; i < stars; i++) { printf("*"); }
    printf("\n");

    if (current != total)
    {
        _print_stars(height, total, current + 1);
    }
}

void print_stars(int height)
{
    int total_recursions = 2 * height - 1;
    _print_stars(height, total_recursions, 1);
}

Answer 5

, , 'main()' :

void PrintTheClms(int width, int stars) {
    printf("*");
    if stars < width then {
      PrintTheClms(width, stars+1);
    }
}

void PrintStars(int  width) {
    PrintTheClms(width, 1);
    printf("\n");
}

void PrintTheRows(int size, int indent) {
    PrintStars(indent);
    if indent < size then {
      PrintTheRows(size, indent+1);
      PrintStars(indent);
    }
}

void PrintTriangle(int size) {
    if size > 0 then {
      PrintTheRows(size, 1);
    }
}

int main() {
    PrintTriangle(6);
    PrintTriangle(11);
    // etc.
    return 0;
}

Very simple - there are no other offers, there are no structural elements, there is no direction flag. However, a lot of procs and many challenges.