Check_If_It_Is_A_Straight_Line.cpp

//Leetcode 1232

class Solution {
public:
    bool checkStraightLine(vector<vector<int>>& coordinates) {
        if(coordinates.size()<3) return true;
        for(int i=2;i<coordinates.size();i++) {
            int dy1=coordinates[i][1]-coordinates[i-1][1];
            int dy0=coordinates[i-1][1]-coordinates[i-2][1];
            int dx1=coordinates[i][0]-coordinates[i-1][0];
            int dx0=coordinates[i-1][0]-coordinates[i-2][0];
            if(dy1*dx0!=dy0*dx1) return false;
        }
        return true;
    }
};