← DSA Foundations
easyProgramming Fundamentals

For, While & Do-While Loops

Use a loop to add every integer from 1 through n.

GeeksforGeeks ↗

Work through the cases

3 examples

Input notation

An integer n, where 0 <= n <= 100000.

Expected result

The sum; print 0 for n = 0.
Case 1

Input

5

Expected output

15
Case 2

Input

0

Expected output

0
Case 3

Input

1

Expected output

1

These notes use simplified input/output notation. The linked platform defines the method signature and judge format.

FROM IDEA TO IMPLEMENTATION

Understand the approach.

Compare the documented approaches below. Brute force, better, and optimal versions appear where available; a direct exercise may need only one approach.

Add every value from 1 through n. This exercise deliberately practices a loop. Time: O(n). Extra space: O(1).

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        ArrayList<Long> values = new ArrayList<>();
        while (in.hasNextLong()) values.add(in.nextLong());
        long[] a = values.stream().mapToLong(Long::longValue).toArray();
        long n = a[0];
        long total = 0; for (long i = 1; i <= n; i++) total += i; System.out.println(total);
    }
}

Reference code. Platform solutions may use supplied node types, imports, or collection libraries; foundational examples are complete programs.