How to print this pyramid pattern?

[shivajikobardan]

How to print this pyramid pattern?

I've built a matrix like this in order to generate logic. The "0" means spaces.

At i=1, j=5 should be printed as star, rest as white spaces
At i=2, j=4,6…
At i=3, j=3,5,7….
At i=4,j=2,4,6,8…
At i=5, j=1,3,5,7,9…

How do I convert this into logic?

 

[FactChecker]

Suppose you are going to print N lines in all. For line n, you can start the line with N-n spaces and then append the two-character string "* " n times.
This Perl code:

[CODE lang="perl" title="This Perl code"]$N=10;
foreach $n (1..$N){
$line = ' 'x($N-$n);
$line = $line . "* "x$n;
print "$line\n";
}[/CODE]
[CODE title="Produces this result"] *
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
* * * * * * * * * *[/CODE]
PS. I forgot to add any trailing space. If that was desired it's easy to do.

 

[shivajikobardan]

Suppose you are going to print N lines in all. For line n, you can start the line with N-n spaces and then append the two-character string "* " n times.
This Perl code:

[CODE lang="perl" title="This Perl code"]$N=10;
foreach $n (1..$N){
$line = ' 'x($N-$n);
$line = $line . "* "x$n;
print "$line\n";
}[/CODE]
[CODE title="Produces this result"] *
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
* * * * * * * * * *[/CODE]
PS. I forgot to add any trailing space. If that was desired it's easy to do.

I only understand javascript,c,c++,java, python . I'm using nested for loops as well.

 

[shivajikobardan]

can anyone help to do with the logic I laid out here? It'd be great.

 

[FactChecker]

Sorry. If this is a schoolwork-type of problem, then we are only allowed to give hints and guidance about your work. (I really shouldn't have given a code solution. It has a slight error anyway.) Can you show how you would start your code and nested loops? You can pick a language or use pseudocode.

 

[shivajikobardan]

Sorry. If this is a schoolwork-type of problem, then we are only allowed to give hints and guidance about your work. (I really shouldn't have given a code solution. It has a slight error anyway.) Can you show how you would start your code and nested loops? You can pick a language or use pseudocode.

Not schoolwork. I don't understand Perl. I'd love hints than code on how to convert that one logic to programming logic.

 

[FactChecker]

But it is still a schoolwork type of problem, so I think that they will want you to follow the schoolwork process.
Hint #1: Your logic clearly is to go through it one line at a time, so the main loop should be the line number.
Hint #2: Even for line 1, you need to know how many total lines you are going to make so you know what value j takes.

 

[PeterDonis]

I don't understand Perl.

The Perl that @FactChecker posted is not that different from what the equivalent Python would be.

 

[shivajikobardan]

n = 5;

for (i = 1; i <= n; i++) {
  for (j = 1; j <= 2 * n - 1; j++) {
    
    document.write("*");
  }
  document.write("<br>");
}

 

[FactChecker]

n = 5;

for (i = 1; i <= n; i++) {
  for (j = 1; j <= 2 * n - 1; j++) {
  
    document.write("*");
  }
  document.write("<br>");
}

You have to actually print the empty spaces. Here are a couple of choices:
1) Start by filling the entire thing with blanks and then use the loops to only place '*'s where they are needed.
2) Within the main loop, place a full set of one line of spaces and then use an inner loop to place the '*'s where they are needed.
3) For each line in the main loop, proceed from left to right and place a space ' ' or a '*' as appropriate at that position.
4) Try to mimic the logic of my Perl program in Javascript.

 

[shivajikobardan]

i know asking code would make this homework problem, but if you could share pseudocode, flowchart or whatever it doesn't make it look like solving other's homework, it'd be helpful.I printed this by watching some tutorial. not exactly this but similar.

n = 5;
for (i = 1; i <= 5; i++) {
  for (space = 1; space <= 5 - i; space++) {
    document.write("y");
  }
  for (j = 1; j <= 2 * i - 1; j++) {
    document.write("x");
  }
  document.write("<br>");
}

 

[FactChecker]

I think that it would help you in general to put comments in your code indicating what the code should do.

// Set number of lines of the artwork
n=5;
// Loop through the lines from i=1 to i=n
for (i=1;i <=n; i++) {
    // start the line with n-i spaces
    for( j=1; j <=n-i; j++) {
        document.write(" ");
    }
    // print "* " i times
    // etc.
}

 

[shivajikobardan]

i know asking code would make this homework problem, but if you could share pseudocode, flowchart or whatever it doesn't make it look like solving other's homework, it'd be helpful.I printed this by watching some tutorial. not exactly this but similar.

n = 5;
for (i = 1; i <= 5; i++) {
  for (space = 1; space <= 5 - i; space++) {
    document.write("y");
  }
  for (j = 1; j <= 2 * i - 1; j++) {
    document.write("x");
  }
  document.write("<br>");
}

y is space and x is *

 

[FactChecker]

y is space and x is *

Ok. Why not use the correct symbols? If you run it does it do what you wanted it to do? If not, you need to make some changes to your logic. (I think you have forgotten some things.)

 

[shivajikobardan]

for (i = 1; i <= 5; i++) {
  for (space = 1; space <= 5 - i; space++) {
    document.write("0");
  }
  for (j = 1; j <= i; j++) {
    document.write("X0");
  }
  document.write("<br>");
}

This has been solved now.

 

[FactChecker]

I assume that you know that you can use the space bar like any other character. So you could print " " and "* " instead of "0" and "X0", respectively.

 

[Ibix]

It's also worth googling for things like "how do I repeatedly print the same string in javascript". That would lead you to the String.repeat function, the use of which would shorten and (I suspect) speed up your code.

 

[shivajikobardan]

I've not learnt about strings yet. Honestly, I'm finding programming very undoable and hard. :( Any tips in physicsforums for it?

 

[Mark44]

can anyone help to do with the logic I laid out here? It'd be great.

$N=10;
foreach $n (1..$N){
    $line = ' 'x($N-$n);
    $line = $line . "* "x$n;
    print "$line\n";
}

I don't speak Perl, but if I had to guess, here's what I think the code above does.
The variables here are $N, $n, and $line. The foreach loop here will execute 10 times, once for each value of $n, which is the loop control variable. $line is a string variable
The first statement in the loop inserts 10 - 1 spaces in $line. The second statement in the loop appends $n asterisks onto the string in $line (1 asterisk the first iteration, 2 asterisks the second time, and so on).
The third statement in the loop prints the string in $line, followed by a newline character.

 

[FactChecker]

I don't speak Perl, but if I had to guess, here's what I think the code above does.
The variables here are $N, $n, and $line. The foreach loop here will execute 10 times, once for each value of $n, which is the loop control variable. $line is a string variable
The first statement in the loop inserts 10 - 1 spaces in $line. The second statement in the loop appends $n asterisks onto the string in $line (1 asterisk the first iteration, 2 asterisks the second time, and so on).
The third statement in the loop prints the string in $line, followed by a newline character.

Yes. And I should be ashamed for:
1) not commenting my code after I have criticized others so often for no comments.
2) using unclear, generic, variable names like N
It is an example of bad coding practices.