naive C implementation

store-credit.c

//
//  main.c
//  cj-store-credit
//
//  Created by Joel Clermont on 4/6/11.
//  Copyright 2011 Orion Group, LLC. All rights reserved.
//

#include <stdio.h>
#include <time.h>

int main (int argc, const char * argv[])
{
    clock_t start = clock();
    
    int N = 0;
    int C = 0;
    int l = 0;
    int caseNum = 0, itemNum = 0;
    int outer = 0, inner = 0;
    int lowIndex = 0, highIndex = 0;
    
    //open input
    FILE *input;
    input = fopen("/Users/joelclermont/Documents/Projects/codejam/cj-store-credit/cj-store-credit/a-small.in", "r");
    
    //open output
    FILE *output;
    output = fopen("/Users/joelclermont/Documents/Projects/codejam/cj-store-credit/cj-store-credit/a-small.out", "w");
    
    //get number of cases
    fscanf(input, "%d", &N);
    
    for(caseNum = 0; caseNum < N; caseNum++) {
        lowIndex = 0; highIndex = 0;
        
        fscanf(input, "%d", &C);
        fscanf(input, "%d", &l);
        int P[l];
        
        for(itemNum = 0; itemNum < l; itemNum++) {
            fscanf(input, "%d", &P[itemNum]);
        }

        for(outer = 0; outer < l; outer++) {
            for (inner = outer + 1; inner < l; inner++) {
                if (P[outer] + P[inner] == C) {
                    lowIndex = outer + 1;
                    highIndex = inner + 1;
                    break;
                }
            }
            if (lowIndex > 0) break;
        }
        
        fprintf(output, "Case #%d: %d %d\n", caseNum + 1, lowIndex, highIndex);

    }
    
    fclose(input);
    fclose(output);
    printf("time elapsed: %f\n", ((double)clock() - start)/CLOCKS_PER_SEC);
    return 0;
}