Day 2: Add C solution part 1

02/solution_1.c

@@ -0,0 +1,31 @@
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+int main(void) {
+    FILE *fp = fopen("input.txt", "r");
+    char buf[16] = {0}, *np;
+    unsigned n, h = 0, v = 0;
+
+    while (fgets(buf, 16, fp) != NULL) {
+        np = strchr(buf, ' ');
+        assert(np != NULL);
+        np++;
+
+        sscanf(np, "%u", &n);
+
+        switch (buf[0]) {
+            case 'd':
+                v += n;
+                break;
+            case 'u':
+                v -= n;
+                break;
+            case 'f':
+                h += n;
+                break;
+        }
+    }
+
+    printf("Answer: %u\n", h * v);
+}