Check If It Is a Straight Line

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:


Solution:

class Solution {
    public boolean checkStraightLine(int[][] coordinates) {
        double a = (double) (coordinates[1][1] - coordinates[0][1]) / (coordinates[1][0] - coordinates[0][0]);
        double y = coordinates[1][1] - a * coordinates[1][0];
        // System.out.println(a + "," + y);
        for (int i = 2; i < coordinates.length; i ++) {
            if (a == Double.POSITIVE_INFINITY) {
                if (coordinates[i][0] != coordinates[i - 1][0]) {
                    return false;
                } else {
                    continue;
                }
            } 
            if (a * coordinates[i][0] + y != (double) coordinates[i][1]) {
                return false;
            }
        }
        return true;
    }
}