3.c

/*
You are given a sorted sequence x0 x1 ... xn -1
(either in the increasing or in the decreasing order)Sequence of
positive numbers, ending with -1.
You can assume that there are atleast two numbers before the ending -1.
Note : -1 is not a part of input. It only signifies that input has ended.
You have to output “True” if there are 3 distinct
numbers in the Input sequance else “False”Kindly do not use arrays in the code.
*/
#include <stdio.h>
int check(p, q, r)
{
    if ((p != q) && (q != r))
    {
        printf("True\n");
    }
    else
    {
        printf("False\n");
    }
}
int main()
{
    int new, p, q, r;
    p = q = r = new = 0;
    scanf("%d", &new);
    while (new != -1)
    {
        r = q;
        q = p;
        p = new;
        printf(" R1 %d %d %d\n", p, q, r);
        check(p, q, r);
        scanf("%d", &new);
        if (new != -1)
        {
            r = q;
            q = p;
            p = new;
            check(p, q, r);
            printf(" R2 %d %d %d\n", p, q, r);
            scanf("%d", &new);
            if (new != -1)
            {
                r = q;
                q = p;
                p = new;
                check(p, q, r);
                printf(" R3 %d %d %d\n", p, q, r);
                scanf("%d", &new);
            }
        }
    }
}