Blogs Hub

Kth Missing Positive Number - Array - Easy - LeetCode - MiniTV

Kth Missing Positive Number - Array - Easy - LeetCode - मिनी टीवी

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)