2280. Minimum Lines to Represent a Line Chart

You are given a 2D integer array stockPrices where stockPrices[i] = [dayi, pricei] indicates the price of the stock on day dayi is pricei. A line chart is created from the array by plotting the points on an XY plane with the X-axis representing the day and the Y-axis representing the price and connecting adjacent points. One such example is shown below:

class Solution {
public:
    int minimumLines(vector<vector<int>>& s) {
        int py = INT_MIN, px = INT_MIN;
        sort(begin(s), end(s));
        int n = s.size(), res = 0;
        for(int i = 0; i < n - 1; i++) {
            int dy = s[i + 1][0] - s[i][0];
            int dx = s[i + 1][1] - s[i][1];
            int gcd = __gcd(dy, dx);
            dy /= gcd;
            dx /= gcd;
            if(dy == py and dx == px) continue;
            res++;
            
            py = dy;
            px = dx;
        }
        return res;
    }
};