2018 day8 part1

1 files changed, 53 insertions, 0 deletions

diff --git a/src/2018/day8/aoc.cpp b/src/2018/day8/aoc.cpp
index 585f144..2f7729f 100644
--- a/src/2018/day8/aoc.cpp
+++ b/src/2018/day8/aoc.cpp
@@ -1,5 +1,58 @@
 #include "aoc.h"
+#include <stack>
+#include <vector>
 
 namespace aoc2018 {
 
+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;
 }
+
+struct header {
+  int nodes;
+  int metas;
+};
+
+int day8(line_view file) {
+  std::vector<int> is;
+  const char* p1 = file.line;
+  const char* p2 = file.line + file.length;
+  while (p1 < p2) {
+    if (*p1 >= '0' && *p1 <= '9') {
+      int d{0};
+      get_number(&p1, &d);
+      is.push_back(d);
+    }
+    p1++;
+  }
+
+  std::stack<header> hs;
+  size_t index{0};
+  int total{0};
+  hs.push({is[index], is[index + 1]});
+  index += 2;
+  while (!hs.empty()) {
+    auto& h = hs.top();
+    if (h.nodes > 0) {
+      hs.push({is[index], is[index + 1]});
+      index += 2;
+      h.nodes -= 1;
+    } else {
+      while (h.metas > 0) {
+        total += is[index];
+        index += 1;
+        h.metas -= 1;
+      }
+      hs.pop();
+    }
+  }
+  return total;
+}
+
+} // namespace aoc2018