getMinDiff.java

/*Input:
K = 3, N = 5
Arr[] = {3, 9, 12, 16, 20}
Output:
11
Explanation:
The array can be modified as
{6, 12, 9, 13, 17}. The difference between 
the largest and the smallest is 17-6 = 11.*/

import java.io.*;
import java.util.*;

  public class Main {

    public static void main(String[] args) throws Exception {
        BufferedReader br =
            new BufferedReader(new InputStreamReader(System.in));
        int tc = Integer.parseInt(br.readLine().trim());
        while (tc-- > 0) {
            String[] inputLine;
            inputLine = br.readLine().trim().split(" ");
            int k = Integer.parseInt(inputLine[0]);
            inputLine = br.readLine().trim().split(" ");
            int n = Integer.parseInt(inputLine[0]);
            int[] arr = new int[n];
            inputLine = br.readLine().trim().split(" ");
            for (int i = 0; i < n; i++) {
                arr[i] = Integer.parseInt(inputLine[i]);
            }

            int ans = new Solution().getMinDiff(arr, n, k);
            System.out.println(ans);
        }
    }
}

class Solution {
    int getMinDiff(int[] arr, int n, int k) {
        
        Arrays.sort(arr);
        int min,max;
        int result = arr[n-1] - arr[0];
        
        for(int i = 1; i < n ; i++)
        {
            if(arr[i] < k)
            continue;
            min = Math.min(arr[i]-k, arr[0] +k);
            max = Math.max(arr[i-1]+k, arr[n-1]-k);
            result = Math.min(result, max-min);
        }
        
        return result;
    }
}