Added older advents

advent_of_code_2018/day6/main2.cc

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+#include <algorithm>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+
+struct Point
+{
+    size_t x;
+    size_t y;
+
+    Point() 
+    : x(0), y(0)
+    { }
+
+    Point(size_t x, size_t y)
+    : x(x), y(y)
+    { }
+};
+
+istream &operator>>(istream& in, Point &point)
+{
+    cin >> point.x;
+    cin.ignore(); // ignore ','
+    cin >> point.y;
+
+    return in;
+}   
+
+inline size_t manhattan_distance(Point const &p1, Point const &p2)
+{
+    return (p1.x > p2.x ? p1.x - p2.x : p2.x - p1.x)
+        + (p1.y > p2.y ? p1.y - p2.y : p2.y - p1.y);
+}
+
+int main()
+{
+    size_t width = 0;
+    size_t height = 0;
+    vector<Point> points;
+
+    while(!cin.eof())
+    {
+        Point point;
+        cin >> point;
+
+        points.push_back(point);
+        width = max(width, point.x + 1);
+        height = max(height, point.y + 1);
+    }
+
+    size_t region_size = 0;
+    size_t distance_limit = 10000;
+    for (size_t idx = 0; idx != width; ++idx)
+    {
+        for (size_t idy = 0; idy != height; ++idy)
+        {
+            size_t sum = 0;
+            Point current {idx, idy};
+            for_each(points.begin(), points.end(), [&](Point const &point)
+            {
+                sum += manhattan_distance(current, point);
+            });
+
+            if (sum < distance_limit)
+                region_size++;
+        }
+    }
+
+    cout << "region size: " << region_size << "\n";
+}