Solve day 6 part 1

1 files changed, 52 insertions, 0 deletions

diff --git a/2018/day06.c b/2018/day06.c
new file mode 100644
index 0000000..5b9552d
--- /dev/null
+++ b/2018/day06.c
@@ -0,0 +1,52 @@
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static int len;
+static struct Point {
+	int x, y;
+} points[50];
+static int area[50];
+
+static int dist(struct Point a, struct Point b) {
+	int x = a.x - b.x;
+	int y = a.y - b.y;
+	return (x < 0 ? -x : x) + (y < 0 ? -y : y);
+}
+
+static int close(struct Point p) {
+	int c = 0;
+	for (int i = 1; i < len; ++i) {
+		if (dist(p, points[i]) < dist(p, points[c])) c = i;
+	}
+	for (int i = 0; i < len; ++i) {
+		if (dist(p, points[i]) == dist(p, points[c]) && i != c) return -1;
+	}
+	return c;
+}
+
+int main() {
+	while (!feof(stdin)) {
+		scanf("%d, %d\n", &points[len].x, &points[len].y);
+		len++;
+	}
+	int maxX = 0, maxY = 0;
+	for (int i = 0; i < len; ++i) {
+		if (points[i].x > maxX) maxX = points[i].x;
+		if (points[i].y > maxY) maxY = points[i].y;
+	}
+	for (int x = 0; x <= maxX; ++x) {
+		for (int y = 0; y <= maxY; ++y) {
+			int c = close((struct Point) { x, y });
+			if (c < 0) continue;
+			if (area[c] < 0) continue;
+			area[c]++;
+			if (x == 0 || x == maxX || y == 0 || y == maxY) area[c] = -1;
+		}
+	}
+	int max = 0;
+	for (int i = 0; i < len; ++i) {
+		if (area[i] > max) max = area[i];
+	}
+	printf("%d\n", max);
+}