Leetcode 1232. Check If It Is a Straight Line

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

解析：直线的表示，可以用斜率式，也可以用两点式，Version 1是斜率式，Version 2是两点式。

• Version 1

class Solution:
    def checkStraightLine(self, coordinates):
        diff_x = coordinates[-1][0] - coordinates[0][0]
        if diff_x == 0:
            for i in range(len(coordinates)):
                if coordinates[i][0] != coordinates[0][0]:
                    return False
            return True

        slope = (coordinates[-1][1] - coordinates[0][1]) / diff_x
        for i in range(len(coordinates) - 1):
            point1 = coordinates[i]
            point2 = coordinates[i + 1]
            if point2[0] - point1[0] == 0:
                return False
            ratio = (point2[1] - point1[1]) / (point2[0] - point1[0])
            if slope != ratio:
                return False

        return True

• Version 2

class Solution:
    def checkStraightLine(self, coordinates):
        x1 = coordinates[0][0]
        y1 = coordinates[0][0]
        x2 = coordinates[-1][0]
        y2 = coordinates[-1][0]

        for i in range(1, len(coordinates) - 1):
            x = coordinates[i][0]
            y = coordinates[i][1]
            if (y - y1)(x2 - x1) != (x - x1)(y2 - y1):
                return False

        return True

Reference

1. https://leetcode.com/problems/check-if-it-is-a-straight-line/