Missing Number Solution

MissingNumber.java

package com.challenge.missingnumber;

import org.apache.commons.lang.ArrayUtils;

public class MissingNumber {

	public static void main(String[] args) {

		int[] num = new int[51];

		for (int i = 1; i <= 50; i++) {
			num[i] = i;
		}

		// Number at index 40 is deleted explicitly
		num = ArrayUtils.remove(num, 40);

		// Now finding and printing the missing number
		System.out.println(findMissingNum(num));
	}

	private static int findMissingNum(int[] num) {

		for (int i = 1; i <= 50; i++) {
			// System.out.println(i);
			if (i != num[i]) {
				return i;
			}
		}
		return (Integer) null;
	}
}