cleanup part one and do part two

[advent21.git] / 17b.c

diff --git a/17b.c b/17b.c
new file mode 100644 (file)
index 0000000..a90c27f
--- /dev/null
+++ b/17b.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+bool is_in(int dx, int dy, int x1, int x2, int y1, int y2)
+{
+       int x = 0, y = 0;
+       while (y >= y1 && x <= x2) {
+               x+=dx;
+               y+=dy;
+               dx = dx == 0 ? 0 : dx-1;
+               dy--;
+               if (x >= x1 && x <= x2 && y >= y1 && y <= y2)
+                       return true;
+       }
+       return false;
+}
+
+int main()
+{
+       int x1, x2, y1, y2, n = 0;
+       scanf("target area: x=%d..%d, y=%d..%d\n", &x1, &x2, &y1, &y2);
+       for (int dy = x2; dy >= y1; dy--)
+               for (int dx = 0; dx <= x2; dx++)
+                       if (is_in(dx, dy, x1, x2, y1, y2))
+                               n++;
+       printf("%d\n", n);
+}