C Code 32 _ To Find p or r Values in nPr Permutation Problem

C Code 32 _ To Find p or r Values in nPr Permutation Problem 

permutations:

Formula to find p is

p(n,r) =   n! / (n-r)!

Program:

#include<stdio.h>

int main()

{

                int n=0,r=0,p=0,i,ch,u=1,l=1;;

                printf("* * * * * nPr Problems on Permutations * * * * *");

                printf("\n\n1 - To find p\n\n2 - To find r\n\nEnter your choice : ");

                scanf("%d",&ch);

                switch(ch)

                {

                case 1:  printf("\n\nEnter the n value : ");

                                                scanf("%d",&n);

                                                printf("\n\nEnter the p value : ");

                                                scanf("%d",&p);

                                                i=n;

                                                while(p>1)

                                                {

                                                                p=p/i;

                                                                i=i-1;

                                                                r=r+1;

                                                }

                                                printf("\n\nThe value of r is : %d",r);

                                                break;

               

                case 2: printf("\n\nEnter the n value : ");

                                                scanf("%d",&n);

                                                printf("\n\nEnter the r value : ");

                                                scanf("%d",&r);

                                                for(i=n;i>=1;i--)

                                                {

                                                                u=u*i;

                                                }

                                                for(i=n-r;i>=1;i--)

                                                {

                                                                l=l*i;

                                                }

                                                p=u/l;

                                                printf("\n\nThe value of p is %d",p);

                                                break;

                                               

                default:

                                                printf("\n\nEnter either 1 or 2 only");

                }

                return 0;

}

Output:

Thank You ...

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