#include<stdio.h>

int main(){

    float a,r;
    float sum=0;

    printf("Enter the first number of the G.P. series: ");
    scanf("%f",&a);

    printf("Enter the common ratio of G.P. series: ");
    scanf("%f",&r);

    if(1 > r)
         sum = a/(1-r);
    else
         sum = a/(r-1);

    printf("\nSum of the infinite G.P. series: %f",sum);

    return 0;
}
Sample output:
Enter the first number of the G.P. series: 1
Enter the common ratio of G.P. series: .5

Sum of the infinite G.P. series: 2.000000

Enter the first number of the G.P. series: 5
Enter the common ratio of G.P. series: 2

Sum of the infinite G.P. series: 5.000000

#include<stdio.h>
int main(){
  int a[50],size,i,big;
  printf("\nEnter the size of the array: ");
  scanf("%d",&size);
  printf("\nEnter %d elements in to the array: ”, size);
  for(i=0;i<size;i++)
      scanf("%d",&a[i]);
  big=a[0];
  for(i=1;i<size;i++){
      if(big<a[i])
           big=a[i];
  }
  printf("\nBiggest: %d",big);
  return 0;
}

#include<stdio.h>
int main(){
  int a[50],size,i,j=0,big,secondbig;
  printf("Enter the size of the array: ");
  scanf("%d",&size);
  printf("Enter %d elements in to the array: ", size);
  for(i=0;i<size;i++)
      scanf("%d",&a[i]);
 
  big=a[0];
  for(i=1;i<size;i++){
      if(big<a[i]){
           big=a[i];
           j = i;
      }
  }

  secondbig=a[size-j-1];
  for(i=1;i<size;i++){
      if(secondbig <a[i] && j != i)
          secondbig =a[i];
  }
  
  printf("Second biggest: %d", secondbig);
  return 0;
}
Sample output:
Enter the size of the array: 5
Enter 5 elements in to the array: 5 3 2 1 0
Second biggest: 3

#include<stdio.h>
int main(){
  int a[50],size,i,j=0,small,secondsmall;
  printf("Enter the size of the array: ");
  scanf("%d",&size);
  printf("Enter %d elements in to the array: ", size);
  for(i=0;i<size;i++)
         scanf("%d",&a[i]);

  small=a[0];
  for(i=1;i<size;i++){
         if(small>a[i]){
               small=a[i];
               j = i;
      }
  }

  secondsmall=a[size-j-1];
  for(i=1;i<size;i++){
         if(secondsmall > a[i] && j != i)
              secondsmall =a[i];
  }

  printf("Second smallest: %d", secondsmall);
  return 0;
}
Sample Output:
Enter the size of the array: 5
Enter 5 elements in to the array: 5 7 3 2 6
Second smallest: 3

#include<stdio.h>
int main(){
  int arr[50];
  int *p;
  int i,j,k,size,n;
  printf("\nEnter size of the array: ");
  scanf("%d",&n);
  printf("\nEnter %d elements into the array: ",n);
  for(i=0;i<n;i++)
    scanf("%d",&arr[i]);
  size=n;
  p=arr;
  for(i=0;i<size;i++){
    for(j=0;j<size;j++){
         if(i==j){
             continue;
         }
         else if(*(p+i)==*(p+j)){
             k=j;
             size--;
             while(k < size){
                 *(p+k)=*(p+k+1);
                 k++;
              }
              j=0;
          }
      }
  }
  printf("\nThe array after removing duplicates is: ");
  for(i=0;i < size;i++){
    printf(" %d",arr[i]);
  }
  return 0;
}