2016 day8

3 files changed, 50 insertions, 4 deletions

diff --git a/src/2016/day8/README.md b/src/2016/day8/README.md
index 33334dc..d664496 100644
--- a/src/2016/day8/README.md
+++ b/src/2016/day8/README.md
@@ -42,4 +42,7 @@ As you can see, this display technology is extremely powerful, and will soon dom
 
 There seems to be an intermediate check of the voltage used by the display: after you swipe your card, if the screen did work, how many pixels should be lit?
 
+--- Part Two ---
+You notice that the screen is only capable of displaying capital letters; in the font it uses, each letter is 5 pixels wide and 6 tall.
 
+After you swipe your card, what code is the screen trying to display?
diff --git a/src/2016/day8/aoc.cpp b/src/2016/day8/aoc.cpp
index fd56a51..573e7c1 100644
--- a/src/2016/day8/aoc.cpp
+++ b/src/2016/day8/aoc.cpp
@@ -2,10 +2,45 @@
 
 namespace aoc2016 {
 
+static void get_number(const char** pp, int* d) {
+  const char* p = *pp;
+  *d = 0;
+  while (*p >= '0' && *p <= '9') {
+    *d = *d * 10 + *p - '0';
+    p++;
+  }
+  *pp = p;
+}
+
+static void get_number(const char* p1, const char* p2, int* ds) {
+  int index{0};
+  while (p1 < p2) {
+    if (*p1 >= '0' && *p1 <= '9') {
+      get_number(&p1, &ds[index++]);
+    }
+    p1++;
+  }
+}
+
 int day8(line_view file) {
-  grid<5, 6> g;
-  g.set(2, 2);
-  return 0;
+  grid<50, 6> g;
+  per_line(file, [&g](line_view lv) {
+    const char* p = lv.line;
+    int ds[2] = {0};
+    get_number(p, p + lv.length, ds);
+    if (p[1] == 'e') {
+      g.set(ds[0], ds[1]);
+    }
+    if (p[1] == 'o' && p[7] == 'c') {
+      g.rotate_v(ds[0], ds[1]);
+    }
+    if (p[1] == 'o' && p[7] == 'r') {
+      g.rotate_h(ds[0], ds[1]);
+    }
+    // g.print();
+    return true;
+  });
+  return g.count();
 }
 
 } // namespace aoc2016
diff --git a/src/2016/day8/aoc.h b/src/2016/day8/aoc.h
index d92a8f7..2313bc9 100644
--- a/src/2016/day8/aoc.h
+++ b/src/2016/day8/aoc.h
@@ -7,9 +7,17 @@ template <size_t W, size_t H>
 struct grid {
   char cells[W * H] = {0};
 
+  int count() const noexcept {
+    int total{0};
+    for (size_t i = 0; i < ARRAY_SIZE(cells); i++) {
+      total += int(cells[i] == 1);
+    }
+    return total;
+  }
+
   void print() {
     for (size_t i = 0; i < ARRAY_SIZE(cells); i++) {
-      printf("%d", cells[i]);
+      printf("%s", cells[i] == 0 ? "." : "#");
       if (i % W == W - 1) {
         printf("\n");
       }