It seems there might have been a confusion with the problem. The problem you solved is "K-diff Pairs in an Array", but the given problem is to find a missing number in a sorted array.

For the missing number problem, you should consider the following approach:

• Since the array is sorted and contains integers from 1 to n with one missing, you can use binary search to efficiently find the missing number.
• The idea is to compare the difference between the value at an index and the index itself. For a complete array without missing numbers, arr[i] should be i+1. If there is a missing number, this difference will change at the point where the number is missing.
• For example, in the array [1,2,3,5,6], the first half (indices 0 to 2) has arr[i] - i = 1, but from index 3 onward, arr[i] - i = 2. So you can use binary search to find the first index where arr[i] - i != 1.

Here is a sample solution in Java for the correct problem:

public int findMissingNumber(int[] arr) {
    int left = 0, right = arr.length - 1;
    while (left <= right) {
        int mid = left + (right - left) / 2;
        if (arr[mid] == mid + 1) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    return left + 1;
}

This solution uses binary search and has O(log n) time complexity and O(1) space complexity.

Please make sure to read the problem statement carefully and understand the requirements before starting to code. Also, ensure that your method name and parameters match the problem.

It appears that you have solved a different problem (likely "K-diff Pairs in an Array") instead of the given problem. Please carefully read the problem statement: we need to find a missing number in a sorted array of integers from 1 to n with one missing. For this problem, you can use a binary search approach to achieve O(log n) time complexity. Your current solution does not address the problem at all. I recommend revisiting the problem and implementing a solution that checks for the missing number by comparing the index and the value at that index. For example, in a sorted array without duplicates, the value should be index+1. If there is a missing number, this relationship will break. You can use binary search to efficiently locate the missing number.