Solution2.java

    boolean isOneLine(int p, int p1, int p2, int[][] points){
        int x = points[p][0];
        int y = points[p][1];
        int x1 = points[p1][0];
        int y1 = points[p1][1];
        int x2 = points[p2][0];
        int y2 = points[p2][1];
        long r = (y - y1)*(x2 - x1);
        long l = (y2 - y1)*(x - x1);
        return r == l;
    }