Given an array arr of positive integers sorted in a strictly increasing order, and an integer k.
Find the kth positive integer that is missing from this array.
Example 1:
Input: arr = [2,3,4,7,11], k = 5 Output: 9 Explanation: The missing positive integers are [1,5,6,8,9,10,12,13,...]. The 5th missing positive integer is 9. Example 2:
Input: arr = [1,2,3,4], k = 2 Output: 6 Explanation: The missing positive integers are [5,6,7,...]. The 2nd missing positive integer is 6.
Constraints:
1 <= arr.length <= 1000 1 <= arr[i] <= 1000 1 <= k <= 1000 arr[i] < arr[j] for 1 <= i < j <= arr.length
public class Solution {
public int FindKthPositive(int[] arr, int k) {
int missing = 0;
int expected = 1;
for(int i=0;i<arr.Length;){
if(arr[i]==expected){
expected++;
i++;
}
else{
missing++;
if(missing==k){
break;
}
expected++;
}
}
if(missing<k){
expected+=k-missing-1;
}
return expected;
}
}Time Complexity: O(n)
Space Complexity: O(1)
