SMALL FACTORIALS

PROBLEM:- SMALL FACTORIALS

You are asked to Calculate the factorials of small positive numbers in the range of 100.

INPUT- First line contains an integer T which represents the number of test cases, followed by T lines each containing a single positive Integer.

 OUTPUT- For each integer, print the factorial of that number.

eg:-

Input:-

2 (test cases)

3

4

Output:-

6

24

SOLUTION:-

#include<stdio.h>

int index;

int main()

{

int t,num,temp,x;

scanf("%d",&t);

while(t--)

{

scanf("%d",&num);

int arr[200]={0};

arr[0]=1;

int i=1;

int current=0;

while(i<=num)

{

index=temp=0;

while(arr[index]>0 || index<current)

{

x=(arr[index]*i)+temp;

arr[index]=x%10;

temp=x/10;

index++;

}

while(temp>0)

{

arr[index]=temp%10;

temp/=10;

index++;

}

i++;

current=index-1;

}

index--;

while(index>=0)

{

printf("%d",arr[index]);

index--;

}

printf("\n");

}

return 0;

}

Trailing Zeroes in the factorial of a Number.

Problem:- Write a program to find the number of zeroes at the end of n!  i.e.  the number of trailing zeroes in the factorial of a number.

Solution:-

#include<stdio.h>

int main()

{

   int n,count=0,i;

    scanf("%d",&n);

        for(i=5;n/i>=1;i*=5)

            count+=n/i;

        printf("No. of zeroes at the end of %d! are:-%d\n",n,count);

return 0;

}

Program in C for the Permutations of a String

Problem :- Write a program in C to print all the permutations of a String.

Solution:-

#include <stdio.h>
#include<string.h>
/* Function to print permutations takes three parameters:-(String, Starting index, Ending index) */
void permutation(char *arr, int i, int n)
{
    int j;
    if (i == n)
    {
        if(strlen(arr)==n)
        {
            printf("%s\n", arr);
        }
    }
    else
    {
        for (j = i; j <= n; j++)
        {
            swap((arr+i), (arr+j));
            permutation(arr, i+1, n);
            swap((arr+i), (arr+j));
        }
    }
}
void swap (char *x, char *y)
{
    char temp;
    temp = *x;
    *x = *y;
    *y = temp;
}
int main()
{
    char arr[100];
    gets(arr);
    int len=strlen(arr);
    permutation(arr, 0, len);
    getchar();
    return 0;
}