<p>Given an array of <code>points</code> where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code> represents a point on the <strong>X-Y</strong> plane, return <em>the maximum number of points that lie on the same straight line</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/plane1.jpg" style="width: 300px; height: 294px;" />
<pre>
<strong>Input:</strong> points = [[1,1],[2,2],[3,3]]
<strong>Output:</strong> 3
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/25/plane2.jpg" style="width: 300px; height: 294px;" />
<pre>
<strong>Input:</strong> points = [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]]
<strong>Output:</strong> 4
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= points.length &lt;= 300</code></li>
	<li><code>points[i].length == 2</code></li>
	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
	<li>All the <code>points</code> are <strong>unique</strong>.</li>
</ul>

class Solution {
public:
    double getSlope(vector<int> point1, vector<int> point2) {
        int pt1_x = point1[0];
        int pt1_y = point1[1];
        int pt2_x = point2[0];
        int pt2_y = point2[1];
        double x = pt1_x - pt2_x;
        double y = pt1_y - pt2_y;
        return y/x;
    }

    int maxPoints(vector<vector<int>>& points) {
        int sz = points.size();
        int max_count = 1;
        
        for(int p1_idx = 0; p1_idx < sz; p1_idx++) {
            unordered_map<double, int> line_count;
            for(int p2_idx = 0; p2_idx < sz; p2_idx++) {
                if(p1_idx == p2_idx) {
                   continue;
                }
                double slope = getSlope(points[p1_idx], points[p2_idx]);
                line_count[slope]++;
            }
            for(auto point: line_count) {
                max_count = max(max_count, point.second + 1);
            }
        }
        return max_count;
    }
};
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