Description

You are given an array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight line in the XY plane.

Example 1:

Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]]
Output: true

Example 2:

Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]]
Output: false

Constraints:

  1. 2 <= coordinates.length <= 1000.
  2. coordinates[i].length == 2.
  3. -10^4 <= coordinates[i][0], coordinates[i][1] <= 10^4
  4. coordinates contains no duplicate point.

分析

题目的意思是：给你一个数组里面的数对是否在同一条直线上，最直观的判断方法是斜率，但是斜率可能会出现分母为0的情况，需要单独来处理，后面发现可以直接比较x1y2==x2y1就行了。这里的x和y是两数的两点的差值，具体过程看代码，也比较简单。

代码

class Solution:
    
    def checkStraightLine(self, coordinates: List[List[int]]) -> bool:
        d={}
        n=len(coordinates)
        
        x1=coordinates[1][0]-coordinates[0][0]
        y1=coordinates[1][1]-coordinates[0][1]
        for i in range(2,n,1):
            x2=coordinates[i][0]-coordinates[i-1][0]
            y2=coordinates[i][1]-coordinates[i-1][1]
            if(x1*y2!= x2*y1):
                return False
        return True

参考文献

​​[LeetCode] Python 3 56ms 92%​​