Solution in C to Round 3 of the 2013 Codehire Cup.

grand_final.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "codehire.h"

int main()
{
    /* Read input */
    char *input = readInput();
    char *line1 = strtok(input, "\n");
    char *line2 = strtok(NULL, "\n");

    /* Parse elevator floors */
    int elevators[5];
    for (int i = 0; i < 5; i++) {
        char *s = strtok(i == 0 ? line1 : NULL, ",");
        elevators[i] = atoi(s);
    }

    /* Parse requests */
    int request_floors[5];
    int request_ages[5];
    int num_requests = 0;
    for (int i = 0; i < 5; i++) {
        char *floor = strtok(i == 0 ? line2 : NULL, ",");
        char *age   = strtok(NULL, ";");
        if (floor && age) {
            request_floors[i] = atoi(floor);
            request_ages[i] = atoi(age);
            num_requests++;
        }
    }

    /* Satisfy requests */
    int output[5];
    for (int i = 0; i < num_requests; i++) {
        /* Find oldest request */
        int oldest = 0;
        for (int j = 1; j < num_requests; j++) {
            if (request_ages[j] > request_ages[oldest]) {
                oldest = j;
            }
        }

        /* Find closest elevator */
        int closest = 0;
        for (int j = 1; j < 5; j++) {
            if (abs(elevators[j] - request_floors[oldest]) < abs(elevators[closest] - request_floors[oldest])) {
                closest = j;
            }
        }
        output[oldest] = closest;

        /* Mark off elevator and request */
        elevators[closest] = 0x7FFFFFFF;
        request_ages[oldest] = -1;
    }

    /* Print output */
    for (int i = 0; i < num_requests; i++) {
        printf(i == 0 ? "%d" : ",%d", output[i]);
    }

    /* Release memory */
    free(input);
    return 0;
}