正方形四个顶点坐标组合 - 所有可能性

以上是保留正方形的四个点坐标的所有可能组合，共21种：

(1,3)(1,4)(2,4)(2,3) (1,3)(2,3)(2,2)(1,2) (1,3)(2,4)(3,3)(2,2) (1,3)(3,3)(3,1)(1,1) (1,3)(3,4)(4,2)(2,1) (1,4)(2,4)(2,3)(1,3) (1,4)(3,4)(3,2)(1,2) (1,4)(4,4)(4,1)(1,1) (2,1)(2,3)(4,3)(4,1) (2,3)(2,4)(3,4)(3,3) (2,3)(3,3)(3,2)(2,2) (2,3)(3,4)(4,3)(3,2) (2,3)(4,3)(4,1)(2,1) (2,4)(3,3)(2,2)(1,3) (2,4)(3,4)(3,3)(2,3) (2,4)(4,3)(3,1)(1,2) (2,4)(4,4)(4,2)(2,2) (3,3)(3,4)(4,4)(4,3) (3,3)(4,3)(4,2)(3,2) (3,4)(4,3)(3,2)(2,3) (3,4)(4,4)(4,3)(3,3)