Java Program to Find the Sum of n Cube Numbers – Sanfoundry

This is the Java Program to Find the Sum of n Cube Numbers.

Problem Description

Given an integer says n, find out the sum of the first n cubed numbers.

Problem Solution

The sum of the first n cubed numbers can be calculated using the formula :

sum = (n*(n+1)/2)2

Program/Source Code

Here is the source code of the Java Program to Find the Sum of n Cube Numbers. The program is successfully compiled and tested using IDE IntelliJ Idea in Windows 7. The program output is also shown below.

  1.  
  2. //Java Program to Find the Sum of n Cube Numbers
  3.  
  4. import java.io.BufferedReader;
  5. import java.io.InputStreamReader;
  6.  
  7. public class SumOfNCubeNumbers {
  8.      // Function to read n and display the sum
  9.     public static void main(String[] args) {
  10.         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  11.         int n;
  12.         System.out.println("Enter the value of n");
  13.         try{
  14.             n = Integer.parseInt(br.readLine());
  15.         }catch (Exception e){
  16.             System.out.println("An error occurred");
  17.             return;
  18.         }
  19.         if(n<0){
  20.             System.out.println("n cannot take negative values");
  21.             return;
  22.         }
  23.         double sum = Math.pow(n*(n+1)/2,2);
  24.         System.out.println("The sum of first " + n + " cube numbers is " + sum);
  25.     }
  26. }

Program Explanation

In the function main(), firstly an integer n is entered and then the sum is calculated as per the line,
double sum = Math.pow(n*(n+1)/2,2). Finally, the sum is displayed.

Time Complexity: O(1).

Runtime Test Cases

 
Case 1 (Simple Test Case):
 
Enter the value of n
15
The sum of first 15 cube numbers is 14400.0

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