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.

## Solution

class Solution { // find slope from point 1 and point 2 // compare the slopes of all other points wrt to the original slope // // Slope of points (x1, y1) and (x2, y2) is: // (y2 - y1) / (x2 - x1) // // Slope of points (x1, y1) and (x3, y3) is: // (y3 - y1) / (x3 - x1) // // for all three points to be on the same line, the slopes should be equal, in other words: // (x3 - x1)*(y2 - y1) = (y3 - y1)*(x2 - x1) // // to avoid running into divide by zero error, use multiplication to find slope public boolean checkStraightLine(int[][] arr) { if(arr == null || arr.length < 3 || arr[0].length == 0) return false; int[] p = arr[0]; int[] q = arr[1]; for(int i = 2; i < arr.length; i++) { int[] curr = arr[i]; if((curr[0] - p[0]) * (q[1] - p[1]) != (curr[1] - p[1]) * (q[0] - p[0])) return false; } return true; } }