1232.Check If It Is a Straight Line
===

###### tags: `Easy`,`Array`,`Math`

[1232. Check If It Is a Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line/description/)

### 題目描述

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.

### 範例

**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.

### 解答
#### Python

class Solution:
    def checkStraightLine(self, coordinates: List[List[int]]) -> bool:
        if len(coordinates) == 2:
            return True
        x0, y0 = coordinates[0]
        x1, y1 = coordinates[1]
        dx, dy = x1 - x0, y1 - y0

        for i in range(2, len(coordinates)):
            x, y = coordinates[i]
            if (x - x0) * dy != (y - y0) * dx:
                return False
        return True

> [name=Yen-Chi Chen][time=Mon, Jun 5, 2023]

#### C++

class Solution {
public:
    bool checkStraightLine(vector<vector<int>>& coordinates) {
        int n = coordinates.size();
        if (n == 2) {
            return true;
        }
        const auto st = coordinates[0];
        int xDiff = (st[0] - coordinates[1][0]);
        int yDiff = (st[1] - coordinates[1][1]);
        for (int i = 2; i < coordinates.size(); i ++) {
            const auto u = coordinates[i];
            if (xDiff * (st[1] - u[1]) != yDiff * (st[0] - u[0])) {
                return false;
            }
        }
        return true;
    }
};

> [name=Jerry Wu][time=5 June, 2023]

### Java

class Solution {
    public boolean checkStraightLine(int[][] coordinates) {
        int x0 = coordinates[0][0], y0 = coordinates[0][1], 
            x1 = coordinates[1][0], y1 = coordinates[1][1];

        int dx = (x1 - x0), dy = (y1 - y0);

        for(int[] coordinate : coordinates) {
            int x = coordinate[0];
            int y = coordinate[1];
            if(dx * (y - y1) != dy * (x - x1)) 
                return false;
        }

        return true;
    }
}

> [name=Ron Chen][time=Mon, June5, 2023]
#### C#

public bool CheckStraightLine(int[][] coordinates) {
    if (coordinates.Length == 2) return true;

    int x1 = coordinates[1][0] - coordinates[0][0];
    int y1 = coordinates[1][1] - coordinates[0][1];

    for (int n = 2; n < coordinates.Length; n++) {
        int xn = coordinates[n][0] - coordinates[0][0];
        int yn = coordinates[n][1] - coordinates[0][1];

        if (x1 * yn != y1 * xn){
            return false;
        }
    }
    return true;
}

> [name=Jim][time=Jun 5, 2023]
#### Javascript

function checkStraightLine(coordinates) {
  const [x1, y1] = coordinates[0];
  const [x2, y2] = coordinates[1];
  for (let i = 2; i < coordinates.length; i++) {
    const [x, y] = coordinates[i];
    if ((y2 - y1) * (x - x1) !== (y - y1) * (x2 - x1)) return false;
  }

  return true;
}

> [name=Marsgoat][time=Jun 5, 2023]
### Reference

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