CODEWITHSUNDEEP
arrays
GANESH BODKE
GANESH BODKE

Reputation: 11

if more than 1 number is missing from array,How to find those missing numbers?

An array is given :array(1,2,3,4,6,8,9). Here 2 numbers are missing. My question is how to find , if more than 1 numbers are missing.

Upvotes: 1

Views: 81

Answers (3)

Andrew Bone
Andrew Bone

Reputation: 7291

In Javascript (the principles should carry over), you can sort it numerically then work your way through the array looking for numbers that aren't there. When you find them you can make a note of it a and move on.

Have a look here:

var numberArray = [1, 2, 3, 4, 6, 8, 9, 15, 12];
var missingArray = [];

function findMissing() {
  var sortedArray = numberArray.sort(function(a, b) {
    return a - b
  });
  var currentNo = sortedArray[0];

  for (let i = 0; i < sortedArray.length; i++) {
    if (sortedArray[i] == currentNo) {
      currentNo++
    } else {
      missingArray.push(currentNo);
      i--;
      currentNo++;
    }
  }
  document.querySelector(".problem").innerHTML = "Array numbers are " + numberArray;
  document.querySelector(".result").innerHTML = "Missing numbers are " + missingArray;
}

findMissing();
<div class="problem"></div>
<div class="result"></div>

Hope this helps.

Upvotes: 0

Eric Duminil
Eric Duminil

Reputation: 54293

You could extract min and max, and compare array to the range from min and max.

Ruby example :

array = [1,2,3,4,6,8,9]
min, max = array.minmax
missing = (min..max).to_a - array
#=> [5,7]

or sort and look for gaps that are bigger than 1

array = [1,2,3,4,6,8,9,12]
array.sort.each_cons(2) do |a,b|
  if (b-1) > a then
    (a+1..b-1).each do |i|
      puts "#{i} is missing"
    end
  end
end

# 5 is missing
# 7 is missing
# 10 is missing
# 11 is missing

Upvotes: 1

alain
alain

Reputation: 12057

If the array is not sorted, sort it, then look for an increase of more than 1 in neighbor elements.

Upvotes: 3

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