2 files changed, 49 insertions, 0 deletions
diff --git a/src/2016/day9/aoc.cpp b/src/2016/day9/aoc.cpp
index 55f4247..4f741d5 100644
--- a/src/2016/day9/aoc.cpp
+++ b/src/2016/day9/aoc.cpp
@@ -2,4 +2,52 @@
 
 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 check(const char** pp, int* t) {
+  int d[2] = {0};
+  const char* p = *pp;
+  int i = 0;
+  while (*p != ')') {
+    if (*p >= '0' && *p <= '9') {
+      get_number(&p, d + i++);
+    }
+    if (*p == '(' || *p == 'x') {
+      p++;
+    }
+  }
+  p += d[0];
+  *t += d[1] * d[0];
+  *pp = p;
+}
+
+int day9(line_view file) {
+  int t0{0};
+
+  const char* p1 = file.line;
+  const char* p2 = p1 + file.length - 1;
+  const char* p = p1;
+
+  while (p < p2) {
+    if (*p == '(') {
+      check(&p, &t0);
+      p++;
+    } else {
+      if (*p != ' ') {
+        t0++;
+      }
+      p++;
+    }
+  }
+  return t0;
+}
+
+} // namespace aoc2016
diff --git a/src/2016/day9/aoc.h b/src/2016/day9/aoc.h
index 95823fe..ab6a78c 100644
--- a/src/2016/day9/aoc.h
+++ b/src/2016/day9/aoc.h
@@ -3,4 +3,5 @@
 
 namespace aoc2016 {
 
+int day9(line_view);
 }