Problem Statement

1Problem Description : 
2Write Algorithm, Flowchart and Program to Find Sum of First n Integers 
3
4
5Example 1 : 
6    Input  : n = 4 
7    Output : 10 
8    Explanation : First 4 integers are 1,2,3 and 4 so sum is 1+2+3+4 = 10 
9
10
11Example 2 : 
12    Input  : n = 10 
13    Output : 55 
14    Explanation : First 10 integers are 1,2,3,..., 10 
15    so sum is = 1+2+3+...+10 = 55 

Algorithm

1Input : input number n 
2Step 1: Start 
3Step 2: Read number n Step 3: Declare sum to 0 and i to 1 
4Step 4: Repeat steps 5 to 7 until i <= n 
5Step 5: update sum as sum = sum + i 
6Step 6: increment i 
7Step 7: Print sum 
8Step 8: Stop 
9Output: sum 

Video Explanation

Flow Chart

Code Implementation

1import java.util.Scanner;
2
3public class SumOfFirstNNumbers {
4
5    public static void main(String[] args) {
6        Scanner sc = new Scanner(System.in);
7
8        // Read n
9        System.out.print("Enter n : ");
10        int n = sc.nextInt();
11
12        // Declare sum and counter variable i
13        int sum = 0;
14        int i;
15
16        // loop continues until i<=n
17        for (i = 1; i <= n; i++) {
18            // update sum
19            sum = sum + i;
20        }
21        // Print sum
22        System.out.printf("Sum of First %d numbers is %d \n", n, sum);
23    }
24}

1Output 1 : 
2Enter n : 4 
3Sum of First 4 numbers is 10