6. Get the positive smallest number that is missing in array

6. Get the positive smallest number that is missing in array

Tool

-Java 8
-CoderPad/sanbox

Solution

import java.io.*;
import java.util.*;
import static java.util.Comparator.*;
/*
 * To execute Java, please define "static void main" on a class
 * named Solution.
 *
 * If you need more classes, simply define them inline.
 */

class Solution
{
  public static void main(String[] args)
  {

//Init array 1
    List <Integer>array = new ArrayList<Integer>();
    array.add(3);
    array.add(4);
    array.add(-1);
    array.add(1);

//Get the smallest num that is missing in array
    int res = getMin(array);

//Print result
    System.out.println("The smallest number that is missing in array is "+res);
    // Init array 2
    List <Integer>array2 = new ArrayList<Integer>();
    array2.add(1);
    array2.add(2);
    array2.add(0);

// Get the smallest num that is missing in array 2
    int res2 = getMin(array2);

//Print result
    System.out.println("Min number that lefts in array 2 is "+res2);
  }
 
  public static int getMin(List<Integer>array)
  {

//Sort the array that identify faster the smallest num
    array.sort(Integer::compareTo);
    int res =0;
    for(int x=0; x<array.size();x++)
    {

//check if next element exists
      if(x+1 < array.size())
      {

//aux is equals to the current element plus one. This will help to identify the missing number
        int aux = array.get(x)+1;

//if aux is less than the next element in array and aux is diferent to 0. Then a element is missing in array
        if(array.get(x+1)> aux && aux >0)
        {

//Res is equeal to the current element in array plus 1 which means that the next number must be the current element plus one
          res =array.get(x)+1;
          break;
        }
      }
    }

//If res is equeal to 0 then the smallest number than is missing in array is the last number in array plus 1
    if(res ==0)
      res = array.get(array.size()-1)+1;
    return res;
  }
 
}