Question

Find out duplicate number between 1 to n numbers. in java

Answer 1

Description:You have got a range of numbers between 1 to N, where one of the number is repeated. You need to write a program to find out the duplicate number.
Code:?1234567891011121314151617181920212223242526272829303132333435package com.java2novice.algos; import java.util.ArrayList;import java.util.List; public class DuplicateNumber {     public int findDuplicateNumber(List<Integer> numbers){                 int highestNumber = numbers.size() - 1;        int total = getSum(numbers);        int duplicate = total - (highestNumber*(highestNumber+1)/2);        return duplicate;    }         public int getSum(List<Integer> numbers){                 int sum = 0;        for(int num:numbers){            sum += num;        }        return sum;    }         public static void main(String a[]){        List<Integer> numbers = new ArrayList<Integer>();        for(int i=1;i<30;i++){            numbers.add(i);        }        //add duplicate number into the list        numbers.add(22);        DuplicateNumber dn = new DuplicateNumber();        System.out.println("Duplicate Number: "+dn.findDuplicateNumber(numbers));    }}