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Java Exercises: Sum of all the elements from all possible subsets of a set formed by first n natural numbers

Java Basic: Exercise-193 with Solution

Write a Java program that accept an integer and find the sum of all the elements from all possible subsets of a set formed by first n natural numbers.

Sample Solution:

Java Code:

import java.util.Scanner;
public class Solution {
 public static void main(String[] args) {
  Scanner in = new Scanner(System.in);
  System.out.print("Input a positive integer: ");
  int n = in .nextInt();
  int result = (n * (n + 1) / 2) * (1 << (n - 1));
  System.out.print("Sum of subsets of n is : " + result);
 }
}

Sample Output: 

Input a positive integer:  25
Sum of subsets of n is : 1157627904

Flowchart:

Flowchart: Java exercises: Sum of all the elements from all possible subsets of a set formed by first n natural numbers

Java Code Editor:

Company:  Bloomberg

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Previous: Write a Java program to rearrange the alphabets in the order followed by the sum of digits in a given string containing uppercase alphabets and integer digits (from 0 to 9).
Next: Write a Java program to find the all positions of a given number in a given matrix. If the number not found print ("Number not found!").

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Java: Tips of the Day

How to remove leading zeros from alphanumeric text?

Regex is the best tool for the job; what it should be depends on the problem specification. The following removes leading zeroes, but leaves one if necessary (i.e. it wouldn't just turn "0" to a blank string).

s.replaceFirst("^0+(?!$)", "")

The ^ anchor will make sure that the 0+ being matched is at the beginning of the input. The (?!$) negative lookahead ensures that not the entire string will be matched.

Test harness:

String[] in = {
    "01234",         // "[1234]"
    "0001234a",      // "[1234a]"
    "101234",        // "[101234]"
    "000002829839",  // "[2829839]"
    "0",             // "[0]"
    "0000000",       // "[0]"
    "0000009",       // "[9]"
    "000000z",       // "[z]"
    "000000.z",      // "[.z]"
};
for (String s : in) {
    System.out.println("[" + s.replaceFirst("^0+(?!$)", "") + "]");
}

Ref: https://bit.ly/2Qdcl8a