Solution.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    static int pairs(int target, int[] arr) {
        Arrays.sort(arr);
        int n = arr.length;
        int count = 0;
        for (int i = 0; i < n - 1; i++) {
            int complement = target + arr[i];
            int index = search(arr, complement, i + 1, n - 1);
            if (index > 0)
                count++;
        }
        return count;
    }

    static int search(int[] arr, int key, int low, int high) {
        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (key < arr[mid])
                high = mid - 1;
            else if(key > arr[mid])
                low = mid + 1;
            else
                return mid;
        }
        return -1;
    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        String[] nk = scanner.nextLine().split(" ");

        int n = Integer.parseInt(nk[0]);

        int k = Integer.parseInt(nk[1]);

        int[] arr = new int[n];

        String[] arrItems = scanner.nextLine().split(" ");
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int i = 0; i < n; i++) {
            int arrItem = Integer.parseInt(arrItems[i]);
            arr[i] = arrItem;
        }

        int result = pairs(k, arr);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}