gistfile1.c

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

#define NUMBER_OF_TRIALS 10000000

bool both_eating(double time_juan, double time_han, double sample);
double simulate(int number_of_trials);
double xrand();

bool both_eating(double time_juan, double time_han, double sample) {
    return sample >= time_juan && sample < time_juan + 0.5
        && sample >= time_han && sample < time_han + 0.5;
}

double simulate(int number_of_trials) {
    int tally = 0;

    int n;
    for (n = 0; n < number_of_trials; n++) {
        double time_juan = xrand() * 3;
        double time_han = xrand() * 3;

        if (both_eating(time_juan, time_han, xrand() * 3)) {
            tally++;
        }
    }

    return (double)tally / (double)number_of_trials;
}

double xrand() {
    return (double)rand() / (double)RAND_MAX;
}

int main(void) {
    srand(time(NULL));

    printf("%f", simulate(NUMBER_OF_TRIALS));

    return 0;
}