LeetCode 1232. Check If It Is a Straight Line_子为空的博客

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:

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

题目大意：二维平面给定任意数量（大于2）的点的坐标，判断这些点是不是位于同一条直线上。

这是一道十分简单的题目，有基本的数学基础的都可以做出来。选定一个基准点，然后依次遍历剩下的点，看看是不是斜率的绝对值都相同即可。为了更加方便地去计算，同时避免考虑斜率正负的问题，这里采用方向向量的方式进行计算。任意选择两个点，并选择其中的一个作为基准点，计算他们之间的方向向量。然后依次遍历剩下的点，计算基准点和其之间的方向向量，只要二者方向相同或相反就说明他们位于一条直线上。

Python代码如下：

class Solution:
    def checkStraightLine(self, coordinates) -> bool:
        if len(coordinates) <= 2:
            return True
        # Direction Vector
        base = [coordinates[0][0] - coordinates[1][0], coordinates[0][1] - coordinates[1][1]]
        for i in range(2, len(coordinates)):
            v = [coordinates[0][0] - coordinates[i][0], coordinates[0][1] - coordinates[i][1]]
            if v[0] * base[1] != v[0] * base[0]:
                return False
        return True
                      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: tru
				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]]
				Problem
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.
Constraints:
2 <= coordinates.length <= 1000
coordinates[i].length ==
				1232. Check If It Is a Straight Line*
https://leetcode.com/problems/check-if-it-is-a-straight-line/submissions/
检查一系列坐标点是否在同一直线上.
C++ 实现 1
看斜率是否一致. 使用乘法比较.
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