593. 有效的正方形 改善丑陋的代码

Posted 2022-08-01 一只大鸽子

解：
题目比较简单，按照定义去判断。
我这里的思路是找到点p1的对角点，然后判断四条边相等（两组对面分别相等的四边形是平行四边形），并且有直角三角形（有直角的，并且四条边相等的平行四边形是正方形）。

最开始的版本，非常长，并且很丑：

from typing import List

class Solution:
    @staticmethod
    def distance2(p1, p2):
        return (p1[0] - p2[0]) ** 2 + (p1[1] - p2[1]) ** 2

    def validSquare(self, p1: List[int], p2: List[int], p3: List[int], p4: List[int]) -> bool:
        p_list = [p1,p2,p3,p4]
        sorted_p_list = sorted(p_list)
        if  sorted_p_list[0] == sorted_p_list[1] or  sorted_p_list[2] == sorted_p_list[3]:
            return False

        distance2s  = [ self.distance2(p1, point) for point in p_list ]
        # 找四条等边
        fourEqualEdge = False
        fourEqualAngle = False
        for point in p_list:
            if point == p1 :
                continue
            if self.distance2(p1, point) == max(distance2s):
                # point 是对点
                other_points = [p  for p in p_list if p != point and p != p1]
                distance2s_p2 = [self.distance2(p, point) for p in other_points]
                distance2s_p1 = [self.distance2(p, p1) for p in other_points]
                edges = distance2s_p1
                edges.extend(distance2s_p2)
                #print(f"edges=edges")
                if all( x == edges[0] for x in edges):
                    fourEqualEdge = True
                if 2*edges[0] == max(distance2s):
                    fourEqualAngle = True
                return  fourEqualEdge and fourEqualAngle

进行了一些修改：
规范了函数名称和变量名称；
去掉了无用的变量：p_list,fourEqualEdge,fourEqualAngle；
使用any()和all() 代替循环。
代码看起来简洁了很多：

from typing import List

class Solution:
    @staticmethod
    def distance(point1, point2):
        """point1和point2距离的平方"""
        return (point1[0] - point2[0]) ** 2 + (point1[1] - point2[1]) ** 2

    def validSquare(self, p1: List[int], p2: List[int], p3: List[int], p4: List[int]) -> bool:
        sorted_p_list = sorted([p1, p2, p3, p4])
        # 如果有重复的点，则返回False
        if any(sorted_p_list[i]==sorted_p_list[i+1] for i in range(3)) :
            return False

        max_distance = max([self.distance(p1, point) for point in sorted_p_list])
        for point in sorted_p_list:
            if self.distance(p1, point) == max_distance:
                # point 是对角点
                other_points = [p for p in sorted_p_list if p != point and p != p1]
                distance2s_p2 = [self.distance(p, point) for p in other_points]
                distance2s_p1 = [self.distance(p, p1) for p in other_points]
                distance2s_p1.extend(distance2s_p2)
                edges = distance2s_p1
                if all(x == edges[0] for x in edges) and 2 * edges[0] == max_distance:
                    return True
                return False