Day 7 - Random Numbers and Recursion

CLASSWORK:
PI Calculation code
/* Program to compute Pi using Monte Carlo methods */
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#define SEED 35791246
void main(void)
{
 int niter=0;
 double x,y,z,pi;
 int count=0; /* # of points in the 1st quadrant of unit circle */
 printf("Enter the number of iterations used to estimate pi: ");
 scanf("%d",&niter);
 /* initialize random numbers */
 srand(SEED);
 count=0;
 for (int i=0; i<niter; i++) {
 x = (double)rand()/RAND_MAX;
 y = (double)rand()/RAND_MAX;
 z = x*x+y*y;
 if (z<=1) count++;
 }
 pi=(double)count/niter*4;
 printf("# of trials= %d , estimate of pi is %g \n",niter,pi);
return 0;

}

Random Number Generator
/* */ 
/* This program generates and prints ten */ 
/* random integers between 1 and RAND_MAX. */ 
#include <stdio.h>
#include <stdlib.h>
int main(void) { 
/* Declare variables. */ 
unsigned int seed; 
int k; 
/* Get seed value from the user. */ 
printf("Enter a positive integer seed value: \n"); 
scanf("%u",&seed); 
srand(seed); /
* Generate and print ten random numbers. */ 
printf("Random Numbers: \n"); 
for (k=1; k<=10; k++) printf("%i ",rand()); 
printf("\n"); 
/* Exit program. */ 
return 0; 
} 
HOMEWORK:
Randon Dice Roll Generator
/* */
/* This program generates and prints ten random */
/* integers between user-specified limits. */
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
/* Declare variables and function prototype. */
unsigned int seed;
int a, b, k, n;
int rand_int(int a,int b);
int count = 0; 
/* Get seed value and interval limits. */
printf("Enter a positive integer seed value: \n");
scanf("%u",&seed);
srand(seed);
printf("Enter integer limits a and b (a<b) for dice roll: \n");
scanf("%i %i",&a,&b);
printf("Enter number of rolls: \n");
scanf("%i",&n);
/* Generate and print N random numbers. */
printf("Dice Rolls: \n");
for (k=1; k<=2*n; k++)
  printf("%i ",rand_int(a,b));
  printf("\t");
if (rand_int(a,b) + rand_int(a,b) == 8)
    count++;
/* Exit program. */
return 0;
}
/* */
/* This function generates a random integer */
/* between specified limits a and b (a<b). */
int rand_int(int a,int b)
{
return rand()%(b-a+1) + a;

}