COMP1721 - Higher Computing 1B

1. This C:

   ---

           int x = 1, y = 10;
           
           while (x < y) {
               printf("%d\n", x*y);
               x = x + 1;
               y = y - 1;
           }
   

   ---

   produces this output:

   ---

   10
   18
   24
   28
   30
   

   ---

   Each execution of the loop produces a line of output containing one number. The first time through the loop, x is 1, y is 10, and so z is 10. Then x is incremented to 2, y is decremented to 9, and the loop repeats. This time, the output is 2*9, or 18. This continues until x becomes 6 and y becomes 5.

2. #include <stdio.h>
   
   int
   main(void) {
       int i,n;
       double total;
           
       printf("How many times should I roll the dice? ");
       scanf("%d", &n);
   
       total = 0.0;
       for (i = 1; i <= n; i++) {
           total += 1.0/i;
       }
       printf("%f\n", total);
       return 0;
   }
   

3. /*
    * estimate pi using the series 4 - 4/3 + 4/5 - 4/7 + 4/9 - 4/11 + .....
    */
   #include <stdio.h>
   
   int
   main(void) {
       double MINIMUM_TERM = 0.000001;
       int i, sign;
       double sum, term;
   
       sum = 0.0;
       sign = 1;
       
       for (i = 1; ; i += 2) {
           term = 4.0 / i;
           if (term < MINIMUM_TERM)
               break;
           sum += sign * term;
           sign *= -1;
       }
       printf("Estimate of pi is %f\n", sum);
       return 0;
   }
   

4. First:

   #include <stdio.h>
   #include <stdlib.h>
   #include <time.h>
   
   int
   main(void) {
       int die1, die2, total; 
           
       srand(time(NULL));
       die1 = 1 + (int)(rand() % 6);
       die2 = 1 + (int)(rand() % 6);
       total = die1 + die2;
       printf("You rolled %d and %d = %d\n", die1, die2, total);
       return 0;
   }
   

   Second:

   #include <stdio.h>
   #include <stdlib.h>
   #include <time.h>
   
   int
   main(void) {
       int die1, die2, total, i, count; 
           
       srand(time(NULL));
       printf("How many times should I roll the dice? ");
       scanf("%d", &count);
       for (i = 0; i < count; i++) {
           die1 = 1 + (int)(rand() % 6);
           die2 = 1 + (int)(rand() % 6);
           total = die1 + die2;
           printf("You rolled %d and %d = %d\n", die1, die2, total);
       }
       return 0;
   }
   

   Third:

   #include <stdlib.h>
   #include <time.h>
   
   int
   main(void) {
       int die1, die2, total, i, count, sevenCount;
           
       srand(time(NULL));
       printf("How many times should I roll the dice? ");
       scanf("%d", &count);
   
       sevenCount = 0;
   
       for (i = 0; i < count; i++) {
           die1 = 1 + (int)(rand() % 6);
           die2 = 1 + (int)(rand() % 6);
           total = die1 + die2;
           printf("You rolled %d and %d = %d\n", die1, die2, total);
           if (total == 7)
               sevenCount++;
       }
       printf("%d 7s were rolled\n", sevenCount);
       return 0;
   }
   

5. #include <stdio.h>
   #include <stdlib.h>
   #include <time.h>
   
   int
   main(void) {
       int die1, die2, total, i, count;
       int tallies[13];
         
       for (i = 2; i <= 12; i++)
           tallies[i] = 0;
   
       srand(time(NULL));
       printf("How many times should I roll the dice? ");
       scanf("%d", &count);
   
   
       for (i = 0; i < count; i++) {
           die1 = 1 + (int)(rand() % 6);
           die2 = 1 + (int)(rand() % 6);
           total = die1 + die2;
           printf("You rolled %d and %d = %d\n", die1, die2, total);
           tallies[total]++;
       }
       for (i = 2; i <= 12; i++) {
           if (tallies[i] > 0)
               printf("%d %ds were rolled\n", tallies[i], i);
       }
       return 0;
   }