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From: DFS <nospam@dfs.com>
Newsgroups: comp.lang.c
Subject: Re: Suggested method for returning a string from a C program?
Date: Wed, 19 Mar 2025 00:42:57 -0400
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On 3/18/2025 11:26 PM, Keith Thompson wrote:
> DFS <nospam@dfs.com> writes:


> There's your problem.
> 
> https://cses.fi/problemset/text/2433
> 
> "In all problems you should read input from standard input and write
> output to standard output."

ha!  It usually helps to read the instructions first.


> The autotester expects your program to read arguments from stdin, not
> from command line arguments.
> 
> It probably passes no arguments to your program, so argv[1] is a null
> pointer.  It's likely your program compiles (assuming the NBSP
> characters were added during posting) and crashes at runtime, producing
> no output.


I KNEW clc would come through!

Pretty easy fixes:

1 use scanf()
2 update int to long
3 handle special case of n = 1
4 instead of collecting the results in a char variable, I print
   them as they're calculated

The algorithm part was very simple and correct.  Later ones won't be so 
easy.  I coded 4 so far (but just submitted this one here), and plan on 
doing all 300.

https://imgur.com/bq0pKIw

Did you hear a boom?

Thanks again!


updated code that passes:
===============================================================
// If n is even, divide it by two.
// If n is odd, multiply it by three and add one.
// Repeat until n is one.
// example: the sequence for n=3 is  3 10 5 16 8 4 2 1

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

int main(int argc, char *argv[])
{
	long n = 0;
	scanf("%ld", &n);
	printf("%ld ",n);
	while(1) {	
		if(n==1) {exit(0);}
		
		if((n % 2) == 0)
			{n /= 2;}
		else
			{n = (n * 3) + 1;}
			
		if(n != 1)
			{printf("%ld ",n);}
		else
			break;
	}	
	printf("1\n");
	return 0;
}	
===============================================================