Cup Stacking exercise from Kattis

cups_stacker_stdin.c

/*
 * 

Stacking Cups

You are programming a cup stacking module for your robot. This robot is equiped with several sensors that can accurately determine the radius and color of a cup. The problem is that there is a glitch in the robot’s core routine that processess sensor inputs so the radius is doubled, if the result of the color sensor arrives to the routine after the radius.

For instance, for a red cup with a radius of 5 units, your module will receive either "red 5" or "10 red" message.

Given a list of messages from the core routine, each describing a different cup, can you put the cups in order of the smallest to the largest?
Input

The first line of the input file contains an integer $N$, the number of cups ($1 \leq N \leq 20$). 
* Next N lines will contain two tokens each, either as "color radius" or "diameter color". 
* The radius of a cup R will be a positive integer less than 1000. 
* The color of a cup C will be a non-empty string of lower case English letters of length at most $20$. 
* All cups will be different in both size and color.
Output

Output colors of cups, one color per line, in order of increasing radius.
Sample Input 1 	Sample Output 1

3
red 10
10 blue
green 7

	

blue
green
red

 * 
*/

#include <stdio.h> /*basic io*/
#include <stdlib.h> /*qsort/malloc/free*/
#include <ctype.h> /*isdigit*/

//Global typedef structure so qsort compare function knows about it
typedef struct Cups
{
	char colour[24];
	int radius;
} cup;

/*qsort compare function*/
int cmpfunc (const void * a, const void * b)
{
  cup *cupA = (cup *)a;
  cup *cupB = (cup *)b;

  //return ( cupB->radius - cupA->radius ); /*sorts big to small*/
  return ( cupA->radius - cupB->radius ); /*sorts small to big*/
}

int main(void)
{

	#define BUFSIZE 64
	
	int line_counter = 0, number_of_cups = 0;
	//char filename_test[]="cups_sample_input.txt";
	char line[BUFSIZE];

	// for dynamic allocation
	cup *cuparray;

	
    //FILE    *fp;

	//fp = fopen (filename_test, "r");
	//if (fp == NULL)
	//{
	//	fputs("Failed to open file.\n", stderr);
	//	return 1;
	//}

	if (fgets(line,BUFSIZE,stdin) != NULL)
	{
		if (isdigit(line[0]) !=  0)
		{
			if (sscanf(line, "%i", &number_of_cups)==1)
			{
				// DEBUG print
				fprintf(stderr, "\ncups=%i\n", number_of_cups);
			}
			else
			{
				fputs("Failed to scan number of cups.\n", stderr);
				return 1;
			}
		}
		else
		{
			fputs("IsNotDigit.\n", stderr);
			return 1;
		}		
	}

	// Can't declare this array until we've read the first line and know how big the file says it needs to be.

	//static
	//cup cuparray[number_of_cups];

	//dynamic
	cuparray = malloc( number_of_cups * sizeof(cup) );
	if(cuparray==NULL)
	{
		fputs("Error: memory not allocated for array.\n", stderr);
		return 1;
	}


	// Now scan the lines into the array of structures.
	// DEBUG print
	fputs("\nReading data...\n\n", stderr);

	while(fgets(line,BUFSIZE,stdin) != NULL)
	{

		// If the first char is a digit, assume diameter-colour line
		if (isdigit(line[0]) !=  0)
		{
			if (sscanf(line, "%i %s", &cuparray[line_counter].radius, cuparray[line_counter].colour)==2)
			{
				//	extra step of halving diameter to make it a radius
				cuparray[line_counter].radius = cuparray[line_counter].radius/2;
				// DEBUG print
				fprintf(stderr, "colour=%s, radius(halved-diameter)=%i\n", cuparray[line_counter].colour, cuparray[line_counter].radius);
			}
			else
			{
				fputs("Failed to scan diameter colour line.\n", stderr);
				return 1;
			}
		}
		// else assume colour-radius line
		else
		{
			if (sscanf(line, "%s %i", cuparray[line_counter].colour, &cuparray[line_counter].radius)==2)
			{
				// DEBUG print
				fprintf(stderr, "colour=%s, radius=%i\n", cuparray[line_counter].colour, cuparray[line_counter].radius);
			}
			else
			{
				fputs("Failed to scan colour radius line.\n", stderr);
				return 1;
			}
		}		
		line_counter++;
	}

	// DEBUG print
	fputs("\nSorting data...\n", stderr);

	qsort(cuparray, (size_t)number_of_cups, sizeof(cup), cmpfunc);

	// DEBUG print
	fputs("\nPrinting sorted data...\n\n", stderr);
	for (line_counter = 0; line_counter<number_of_cups; line_counter++)
	{
		printf("colour=%s, radius=%i\n", cuparray[line_counter].colour, cuparray[line_counter].radius);
	}

// FINAL OUTPUT
	fputs("\nPrinting final output...\n\n", stderr);
	for (line_counter = 0; line_counter<number_of_cups; line_counter++)
	{
		printf("%s\n", cuparray[line_counter].colour);
	}

	//free malloc'ed array
	free(cuparray);

	//close file
	//fclose(fp);

	return 0;
}