Likou punch card 2021.1.17 dotted into a line

Topic:
There are some points in an XY coordinate system. We use the array coordinates to record their coordinates respectively. Coordinates[i] = [x, y] represents the point with the abscissa as x and the ordinate as y.

Please judge whether these points are on the same straight line in the coordinate system. If yes, return true, otherwise, return false.

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

Code:

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