1232_Check_if_its_a_Straight_line

// https://leetcode.com/problems/check-if-it-is-a-straight-line/

class Solution {
    int x1=-1,x2=-1,y1=-1,y2=-1;
        
    public boolean checkStraightLine(int[][] coordinates) {
        if(coordinates.length<2)
            return false;
        x1 = coordinates[0][0];
        y1 = coordinates[0][1];
        x2 = coordinates[1][0];
        y2 = coordinates[1][1];
        for(int i=2;i<coordinates.length;i++) {
            if(checkEquation(coordinates[i][0],coordinates[i][1])==false)
                return false;
        }
        return true;
    }
    public boolean checkEquation(int x, int y) {
       int lhs =0,rhs=0;
        if(x1!=x2)
            lhs = (int)((x-x1)/(x2-x1));
        if(y1!=y2)
            rhs = ((int)((y-y1)/(y2-y1)));
        if(lhs == rhs || (lhs == 0 && x1==x) || (rhs==0 && y1==y))
            return true;
        else
            return false;
    }
}

// Other approach

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