Write a Java program that computes the summation of 1 to n?

Answer 1

Increment your counter two at a time. Example, for n = 100:

n = 100;

sum = 0;

for (int i = 1; i <= n; i+=2) sum += i;

Another option (less efficient) is to loop through ALL integers, and check whether the number is odd:

n = 100;

sum = 0;

for (int i = 1; i <= n; i++) {

if (i % 2 == 1)

sum += i;

}

Or:

if (min%2==0) min= min+1;

if (max%2==0) max= max-1;

sum = ((max-min)/2 + 1) * (min+max) / 2;

Answer 2

class Add

{

public static void main (String args[])

{

int n = 15;

int sum = 0;

for(int i = n;i>=0;i--)

sum = sum + i;

System.out.println("Sum = "+ sum);

}

}

Answer 3

The below method is written in the assumption that, the n numbers are sent as an ArrayList of Integer values.

public void computeSumAndAvg(ArrayList lst){

Iterator itr = lst.iterator();

int sum = 0;

float average = 0;

int count = 0;

while(itr.hasNext(){

Integer val = (Integer) itr.next();

sum = sum + val.intValue();

count++;

}

average = sum/count;

System.out.println("Sum is: " + sum) ;

System.out.println("Average is: " + average) ;

}

Answer 4

It isn't clear what you mean by the "difference of N numbers". "Difference" is normally defined just for two numbers, so you would need to clarify what calculations are to be done in the case of more than two numbers.

Answer 5

That would depend in a great deal on how those N numbers are presented by the program. However, a general pseudocode might be:

Do whatever housekeeping necessary to connect with the group of numbers (define a hardcoded array, open a file of numbers, format a user interface popup, etc.)

Initialize sum variable to 0

For some set of conditions (limits of the array, set and test an EOF flag, get an 'alldone' indication from the user, etc.) do the following

Get the next number by whatever means relevant

If end condition not reached, add obtained value to sum variable

When loop completed, display final result

Answer 6

Something like this - assuming you already have an array called "myArray":

int sum = 0;

for(int element : myArray)

sum += element;

Note: The "for" is the "for each" variety; in other words, it is run once for each element of the array.

Answer 7

public int sum(){

int sum = 0;

for (int i = 0; i <= n; i++)

sum+=i;

return sum;

}

Answer 8

Something like this:
int n = 100;

int sum = 0;

for(int i = 1; i <= n; i++) {sum += i;}

System.out.println("The sum is: " + sum);