1539. Kth Missing Positive Number.cpp

class Solution {
public:
    int findKthPositive(vector<int>& arr, int k) {
        int left = 0, right = arr.size()-1;

        while(left <= right){
            int mid = left + (right-left)/2;

            if(arr[mid]-mid-1 < k){
                left = mid+1;
            } else{
                right = mid-1;
            }
        }

        return left+k;
    }
};