poj2785java

以下是使用Java解决POJ 2785问题的示例代码：

import java.util.Arrays;

public class POJ2785 {
    public static void main(String[] args) {
        int[] A = {1, 2, -3, 4, -1, -2, 3, -4};
        int n = A.length;
        int[] x = new int[n * n];
        int[] y = new int[n * n];

        int idx = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                x[idx] = A[i] + A[j];
                y[idx] = -(A[i] + A[j + 2]);
                idx++;
            }
        }

        Arrays.sort(y);

        int count = 0;
        for (int i = 0; i < n * n; i++) {
            int target = x[i];
            int left = 0;
            int right = n * n - 1;

            while (left < right) {
                int mid = (left + right) / 2;
                if (y[mid] < target) {
                    left = mid + 1;
                } else {
                    right = mid;
                }
            }

            if (y[left] == target) {
                count++;
            }
        }

        System.out.println(count);
    }
}