1 files changed, 77 insertions, 0 deletions
diff --git a/ntu/moco.c b/ntu/moco.c
new file mode 100644
index 0000000..9354a0f
--- /dev/null
+++ b/ntu/moco.c
@@ -0,0 +1,77 @@
+#include <stdio.h>
+
+typedef struct {
+	short x;
+	short y;
+} point_t;
+
+point_t a, b, c, d;
+
+long long cross_product(point_t m, point_t n, point_t p, point_t q)
+{
+	return (n.x - m.x) * (q.y - p.y) - (q.x - p.x) * (n.y - m.y);
+}
+
+char convex()
+{
+	if (cross_product(a, c, c, b) * cross_product(a, c, c, d) > 0)
+		return 0;
+	if (cross_product(b, d, d, a) * cross_product(b, d, d, c) > 0)
+		return 0;
+	return 1;
+}
+
+void swap(point_t *m, point_t *n)
+{
+	short tmp = m->x;
+	m->x = n->x;
+	n->x = tmp;
+	tmp = m->y;
+	m->y = n->y;
+	n->y = tmp;
+}
+
+long long dot_product(point_t m, point_t n, point_t p, point_t q)
+{
+	return (n.x - m.x) * (q.x - p.x) + (n.y - m.y) * (q.y - p.y);
+}
+
+char f2()
+{
+	return !dot_product(a, b, b, c);
+}
+
+char f3()
+{
+	return !dot_product(a, c, b, d);
+}
+
+char f4()
+{
+	return (a.x + c.x == b.x + d.x) && (a.y + c.y == b.y + d.y);
+}
+
+int main()
+{
+	scanf("%hd %hd %hd %hd %hd %hd %hd %hd",
+	      &a.x, &a.y, &b.x, &b.y, &c.x, &c.y, &d.x, &d.y);
+
+	if (!convex()) {
+		swap(&a, &b);
+		if (!convex())
+			swap(&b, &c);
+	}
+
+	char val = 5;
+	if (f4()) {
+		val = 4;
+		if (f2())
+			val = 2;
+		if (f3())
+			val--;
+	}
+
+	printf("%hhd\n", val);
+
+	return 0;
+}