Max Points on a Line
Desicription
Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.
Example 1:
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| Input: [[1,1],[2,2],[3,3]] Output: 3 Explanation: ^ | | o | o | o +-------------> 0 1 2 3 4
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Example 2:
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| Input: [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]] Output: 4 Explanation: ^ | | o | o o | o | o o +-------------------> 0 1 2 3 4 5 6
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Solution
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class Solution { public: int maxPoints(vector<Point>& points) { int res = 0; for(int i = 0; i < points.size(); i++) { int samePoints = 1; int maxNum = 0; unordered_map<long double, int> mp; for(int j = i+1; j < points.size(); j++) { if(points[i].x == points[j].x && points[i].y == points[j].y) samePoints++; else if(points[i].x == points[j].x) mp[INT_MAX]++; else { long double slope = (long double) (points[j].y - points[i].y) / (long double) (points[j].x - points[i].x); mp[slope]++; } } for(auto it : mp) maxNum = max(maxNum, it.second); res = max(res, maxNum + samePoints); } return res; } };
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