task_03.c

/*

    task_03.c

    Task from:
    https://www.facebook.com/photo/?fbid=467781461516432&set=gm.1858927787627453

The basic problem is to assume you have an opaque bag containing 20 balls,
12 of which are red and 8 of which are green.

You jiggle the bag to mix the balls and then remove balls, one at a time,
without looking in the bag.

You will write a program that simulates this activity and reports
the order of the balls as they are withdrawn from the bag.

You are to report each ball as an "R" or a "G" indicating if the ball is red or green.

You should end up with 20 letters printed to the screen.
8 G's and 12 R's in some random order.

Important: At each step, you should simulate the right probabilities.

For example, in the beginning, the probabilities of drawing a red ball is 60%
and a green ball is 40%.

You are to count and keep track of the longest streak of green balls
experienced in the random drawing.
You are to report this longest streak as a number, after all 20 balls have been selected.

Sample output: RGGGRRRGRGGRGRRRGRRR 3



Necessary code lines to generate random numbers:

    #include<stdlib.h>  // RAND_MAX is defined in stdlib.h
    #include<time.h>    // for random number generator

in function main():

    time_t t;   // for random number generator

    // Intializes random number generator, should only be called once.
    srand((unsigned) time(&t));

    // function rand() returns an integer value between 0 and RAND_MAX.
    number = rand();

    number = rand() % 9 + 1;    // generate random number between 1 and 9


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>
#include<stdlib.h>  // RAND_MAX is defined in stdlib.h
#include<time.h>    // for random number generator

#define MAX_SIZE 100

// Function to print array of characters, n is number of characters in array arr[],
// text describes the shown array arr[]
void printArray( char *text, char arr[], int n ){
    int i;
    printf("%s", text );
    for(i=0; i<n; i++)
        printf("%2c", *(arr+i) );
    printf("\n");
}

// This function is not used here.
// generate and return random integer number between lower and upper, including them.
int get_random_integer_from_lower_to_uppper(int lower, int upper)
{
    // generate and return random number between 0 and upper-1
    //return( rand() % upper );

    // generate and return random number between 1 and upper
    //return( rand() % upper + 1 );

    // generate and return random integer number between lower and upper
    return( (rand() % (upper - lower + 1)) + lower );
}


int main(void){
    int i, position, num=20, num_red=12, num_green=num-num_red, longest_subarray_of_G=0, temp_subarray_of_G=0;
    time_t t;       // for random number generator
    char arr[MAX_SIZE];

    // Intializes random number generator, should only be called once.
    srand((unsigned) time(&t));

    // Fill the array with num_red 'R'.
    i=num_red;
    while(i>0){
        position = rand() % num;    // generate random number between 0 and num
        if(arr[position]!='R'){
            arr[position]='R';
            i--;
        }
    }

    // Fill the remaining num_green empty spaces in the array with 'G'
    for(i=0;i<num;i++)
        if(arr[i]!='R')
            arr[i]='G';

    printArray("\n Array is: \n\n",arr,num);

    // Find longest subarray of 'G'
    for(i=0;i<num;i++)
        if(arr[i]=='G'){
            temp_subarray_of_G++;
            if(longest_subarray_of_G < temp_subarray_of_G)
                longest_subarray_of_G = temp_subarray_of_G;
        }else
            temp_subarray_of_G=0;

    printf("\n Longest subarray of 'G' is %d \n\n", longest_subarray_of_G);

    return 0;
} // main()