给X轴上N个点，这N个点可以组成 N*（N – 1）/ 2 条线，求第K条线段的长度

如Points : [0, 1, 3, 5] ，当K = 5时，结果是4

package other;

public class Main {

	public static void main(String args[]) {
		Main main = new Main();
		int n = 4;
		int points[] = { 0, 1, 3, 5 };
		int k = 5;
		int resurt = main.getLineLength(points, n, k);
		System.out.println(resurt);
	}

	public int getLineLength(int[] points, int n, int k) {
		int length = n * (n - 1) / 2;
		int lineLengths[] = new int[length];
		for (int i = 0; i < points.length; i++) {
			for (int j = i + 1; j < points.length; j++) {
				lineLengths[--length] = points[j] - points[i];
			}
		}
		return lineLengths[lineLengths.length-k];
	}
}