From 138af62cd2349dbd0beb5096058c576945986908 Mon Sep 17 00:00:00 2001
From: Alex Karle <alex@alexkarle.com>
Date: Thu, 2 Dec 2021 09:45:26 -0500
Subject: [PATCH] day2: Add C implementation

Things learned:

* Use scanf instead of fscanf (stdin implied)
* scanf has a max-len specifier to make it somewhat mem safe
---
 2/c/a.c  | 24 ++++++++++++++++++++++++
 2/c/b.c  | 26 ++++++++++++++++++++++++++
 Makefile |  4 ++++
 3 files changed, 54 insertions(+)
 create mode 100644 2/c/a.c
 create mode 100644 2/c/b.c

diff --git a/2/c/a.c b/2/c/a.c
new file mode 100644
index 0000000..dcab638
--- /dev/null
+++ b/2/c/a.c
@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main(void) {
+    int depth = 0;
+    int pos = 0;
+    int val;
+    char comm[256];
+    while(scanf("%255s %d\n", comm, &val) != EOF) {
+        if (!strcmp(comm, "forward")) {
+            pos += val;
+        } else if (!strcmp(comm, "up")) {
+            depth -= val;
+        } else if (!strcmp(comm, "down")) {
+            depth += val;
+        } else {
+            fprintf(stderr, "bad command: %s\n", comm);
+            exit(1);
+        }
+    }
+    printf("%d\n", pos * depth);
+    return 0;
+}
diff --git a/2/c/b.c b/2/c/b.c
new file mode 100644
index 0000000..3f3faee
--- /dev/null
+++ b/2/c/b.c
@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+int main(void) {
+    int depth = 0;
+    int pos = 0;
+    int aim = 0;
+    int val;
+    char comm[256];
+    while(scanf("%255s %d\n", comm, &val) != EOF) {
+        if (!strcmp(comm, "forward")) {
+            pos += val;
+            depth += val * aim;
+        } else if (!strcmp(comm, "up")) {
+            aim -= val;
+        } else if (!strcmp(comm, "down")) {
+            aim += val;
+        } else {
+            fprintf(stderr, "bad command: %s\n", comm);
+            exit(1);
+        }
+    }
+    printf("%d\n", pos * depth);
+    return 0;
+}
diff --git a/Makefile b/Makefile
index 9aec0fe..19e8b4a 100644
--- a/Makefile
+++ b/Makefile
@@ -3,6 +3,8 @@ CFLAGS = -g -O2 -Wall -Wpedantic -Wextra
 TARGETS = \
 	  1/c/a \
 	  1/c/b \
+	  2/c/a \
+	  2/c/b \
 
 .PHONY: all
 all: $(TARGETS)
@@ -11,6 +13,8 @@ all: $(TARGETS)
 clean:
 	rm -f $(TARGETS)
 
+2/c/b: 2/c/b.c
+2/c/a: 2/c/a.c
 1/c/b: 1/c/b.c
 1/c/a: 1/c/a.c
 	$(CC) $(CFLAGS) -o $@ $<
--
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