Problem Statement

1Problem Description :  
2Write algorithm and a flowchart that will compute the sum of two numbers. if the sum is below or equal to twenty, two numbers will be entered again. if the sum is above 20, it will display the sum.

Algorithm

1Input : Two numbers num1 and num2
2Step 1: Start 
3Step 2: Declare sum to 0  (This is optional step, during step5 we can add declaration and assign directly as well) 
4Step 3: Read number num1
5Step 4: Read number num2
6Step 5: Add num1 and num2 and assign result to variable sum 
7Step 6: If sum is greater than 20 Goto Step 7, else Goto Step 3
8Step 7: Print sum 
9Step 8: Stop 
10Output: Sum of num1 and num2  

Flowchart

Code Implementation

1import java.util.Scanner;
2
3public class SumOfTwoNumbersWithSumGreaterThan20 {
4
5  public static void main(String[] args) {
6    // Initialize scanner to which is used to read inputs
7    Scanner sc = new Scanner(System.in);
8
9    while (true) {
10      // Read number1 and number 2
11      System.out.print("Enter num1: ");
12      int num1 = sc.nextInt();
13      System.out.print("Enter num2: ");
14      int num2 = sc.nextInt();
15
16      // calculate sum
17      int sum = num1 + num2;
18
19      // if sum is greater than 20 print it
20      // and break the loop
21      if (sum > 20){
22        System.out.printf("Sum is %d \n", sum);
23        break;
24      }
25      // continue for next input
26      System.out.printf("sum: %d is less than 20, Try again\n", sum);
27    }
28  }
29}

Output 1 :

1Enter number1: 1
2Enter number2: 2
3sum: 3 is less than 20, Try again
4Enter number1: 1
5Enter number2: 43
61 + 43 = 44

Output 2 :

1Enter number1: 21
2Enter number2: 12 
321 + 12 = 33