# k-th missing element in sorted array in C++

In this tutorial, we are going to write a program that finds out the k-th missing element in the given sorted array.

Find the k-th number that is missing from min to max in the given unsorted array. Let's see the steps to solve the problem.

• Initialise the sorted array.
• Initialise two variables difference and count with k.
• Iterate over the array.
• If the current element is not equal to the next element.
• Find the difference between the two numbers.
• If the difference is greater than or equal to k, then return current element plus count.
• Else subtract difference from the count.
• Return -1.

## Example

Let's see the code.

Live Demo

#include <bits/stdc++.h>
using namespace std;
int findMissingNumber(int arr[], int k, int n) {
int difference, count = k;
for(int i = 0 ; i < n - 1; i++) {
if ((arr[i] + 1) != arr[i + 1]) {
difference = arr[i + 1] - arr[i] - 1;
if (difference >= count) {
return arr[i] + count;
}else {
count -= difference;
}
}
}
return -1;
}
int main() {
int arr[] = { 1, 2, 3, 5, 10 }, n = 5;
int k = 3;
cout << findMissingNumber(arr, k, n) << endl;
return 0;
}

## Output

If you run the above code, then you will get the following result.

7

## Conclusion

If you have any queries in the tutorial, mention them in the comment section.