Java

Question

write a program to find sum of all natural numbers from one to hundered in java

Answer 1

public class Program
{
public static void main(String[] args) {
int sum = 0;
for(int i=1, j=100; i<=50; i++, j--) {
sum += (i+j);
}
System.out.println(sum);
}
}

A little homage to immortal genius of Gauss.... once it was a child, Gauss' teacher gave the class task to sum numbers from 1 to 100, to take them busy for an hour or so.

After a few seconds, Gauss answered "5050"!

He reasoned so: sum 1 and 100, you get 101. Sum 2 and 99, you get 101. Sum 3 and 98, you get 101. And so on, for all 50 couples you can form. So, result is 101 * 50 = 5050.

Answer 2

it's an arithmetic progression, then:
sum = ((1+100)/2)*100;

(S = ((a1+a2)/2)*n)

why is it better? Cause complexety of codes before this is O(n), this code is O(1).

Answer 3

if anybody know the answer

Answer 4

write a program to find sum of all natural numbers from one to hundered

Answer 5

Now please improve my code taking a number from user as input, and outputting the sum of all numbers from 1 to that number :)

Answer 6

wrong answer

Answer 7

I assure you 5050 is the right answer :)

Answer 8

But perhaps you wanted this:

public class Program
{
public static void main(String[] args) {
int sum = 0;
for(int i=1; i<=100; i++) {
sum += i;
}
System.out.println(sum);
}
}