From: Mart Lubbers <mart@martlubbers.net>
Date: Fri, 17 Dec 2021 08:11:51 +0000 (+0100)
Subject: day 17 part one
X-Git-Url: https://git.martlubbers.net/?a=commitdiff_plain;h=5e45affee88ae30205ab85c5e091a9f07d4565d3;p=advent21.git

day 17 part one
---

diff --git a/16b.c b/16b.c
index 437560e..6c93a16 100644
--- a/16b.c
+++ b/16b.c
@@ -14,13 +14,8 @@ struct stream { int pos; char *buf; };
 int next(struct stream *f)
 {
 	int r;
-	if (*f->buf == '\0') {
-		if ((r = getchar()) == EOF) {
-			printf("EOF\n");
-			exit(1);
-		}
+	if (*f->buf == '\0')
 		f->buf = hex2bin[r];
-	}
 	r =*(f->buf++) == '1' ? 1 : 0;
 	f->pos++;
 	return r;
diff --git a/17.txt b/17.txt
new file mode 100644
index 0000000..58c356f
--- /dev/null
+++ b/17.txt
@@ -0,0 +1 @@
+target area: x=150..193, y=-136..-86
diff --git a/17a.c b/17a.c
new file mode 100644
index 0000000..2140026
--- /dev/null
+++ b/17a.c
@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+bool is_in(int dx, int dy, int x1, int x2, int y1, int y2, int *maxy)
+{
+	int x = 0, y = 0, my = 0;
+	while (y >= y2 && x <= x2) {
+		x+=dx;
+		y+=dy;
+		dx = dx == 0 ? 0 : dx-1;
+		dy--;
+		if (y > my)
+			my = y;
+		if (x >= x1 && x <= x2 && y >= y1 && y <= y2)  {
+			if (my > *maxy)
+				*maxy = my;
+			return true;
+		}
+	}
+	return false;
+}
+
+int main()
+{
+	size_t len;
+	char *buf = NULL;
+	if (getline(&buf, &len, stdin) == -1)
+		return 1;
+	printf("%s", buf);
+
+	while (*buf++ != '=');
+
+	int x1 = strtol(buf, &buf, 10);
+	buf+=strlen("..");
+	int x2 = strtol(buf, &buf, 10);
+	buf+=strlen(", y=");
+	int y1 = strtol(buf, &buf, 10);
+	buf+=strlen("..");
+	int y2 = strtol(buf, &buf, 10);
+
+	int maxy = 0;
+	for (int dy = x2; dy >= 0; dy--)
+		for (int dx = 1; dx <= x2; dx++)
+			if (is_in(dx, dy, x1, x2, y1, y2, &maxy))
+				break;
+	printf("%d\n", maxy);
+}
diff --git a/17e.txt b/17e.txt
new file mode 100644
index 0000000..a07e02d
--- /dev/null
+++ b/17e.txt
@@ -0,0 +1 @@
+target area: x=20..30, y=-10..-5