Create Max_Points_on_a_Line.cc

Author: iphkwan

Max_Points_on_a_Line.cc

@@ -0,0 +1,43 @@
+/**
+ * Definition for a point.
+ * struct Point {
+ *     int x;
+ *     int y;
+ *     Point() : x(0), y(0) {}
+ *     Point(int a, int b) : x(a), y(b) {}
+ * };
+ */
+class Solution {
+public:
+    int maxPoints(vector<Point> &points) {
+        if (points.size() <= 1)
+            return points.size();
+        
+        unordered_map<double, int> hash;
+        double fSlope;
+        int ret = 0, iVertical, iSame, iMaxValue;
+        for (int i = 0; i < points.size(); i++) {
+            hash.clear();
+            iVertical = iSame = iMaxValue = 0;
+            for (int j = 0; j < points.size(); j++) {
+                if (points[i].x == points[j].x) {
+                    //same
+                    if (points[i].y == points[j].y) {
+                        iSame++;
+                    } 
+                    //vertical
+                    else {
+                        iVertical++;
+                    }
+                }
+                else {
+                    fSlope = (points[i].y - points[j].y) * 1.0 / (points[i].x - points[j].x);
+                    hash[fSlope]++;
+                    iMaxValue = max(iMaxValue, hash[fSlope]);
+                }
+            }
+            ret = max(ret, max(iMaxValue, iVertical) + iSame);
+        }
+        return ret;
+    }
+};