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-rw-r--r--other/max_points_line.cpp50
1 files changed, 50 insertions, 0 deletions
diff --git a/other/max_points_line.cpp b/other/max_points_line.cpp
new file mode 100644
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--- /dev/null
+++ b/other/max_points_line.cpp
@@ -0,0 +1,50 @@
+#include "leetcode.h"
+
+class Point { // basic coordinate geometry
+public:
+ double x, y;
+ Point(double x, double y) {
+ this->x = x;
+ this->y = y;
+ }
+};
+
+class Solution {
+public:
+ int maxPoints(vvd & points) {
+ int n = points.size(), ans = 0;
+ if (n <= 2) // 2 or less means points are always collinear
+ return n;
+ vector<Point> coordinates;
+ for (auto &i : points) {
+ Point k = Point((double)i[0], (double)i[1]);
+ coordinates.push_back(k);
+ }
+ for (int i = 0; i < n; i++)
+ for (int j = 0; j < n; j++) {
+ int cnt = 0;
+ for (int k = 0; k < n; k++)
+ if (i != j && j != k && i != k)
+ if (isCollinear(coordinates[i], coordinates[j], coordinates[k]))
+ cnt++;
+ ans = max(cnt + 2, ans);
+ }
+ return ans;
+ }
+
+private:
+ bool isCollinear(Point a, Point b,
+ Point c) { // checks if 3 given points lie on same line
+ double i = (b.y - a.y) / (b.x - a.x);
+ double j = (c.y - b.y) / (c.x - b.x);
+ return i == j;
+ }
+};
+
+int main() {
+ Solution obj;
+ vvd points1 = {{1, 1}, {2, 2}, {3, 3}},
+ points2 = {{1, 1}, {3, 2}, {5, 3}, {4, 1}, {2, 3}, {1, 4}};
+ cout << obj.maxPoints(points1) << endl; // expect: 3
+ cout << obj.maxPoints(points2) << endl; // expect: 4
+}