2019 day5 part1

1 files changed, 92 insertions, 0 deletions

diff --git a/src/2019/day5/aoc.cpp b/src/2019/day5/aoc.cpp
index f0cbc1b..4c310e1 100644
--- a/src/2019/day5/aoc.cpp
+++ b/src/2019/day5/aoc.cpp
@@ -1,5 +1,97 @@
 #include "aoc.h"
+#include <vector>
 
 namespace aoc2019 {
 
+static int input = 1;
+static std::vector<int> outputs = {};
+
+void get_number(const char** pp, int* d) {
+  const char* p = *pp;
+  int sign = 1;
+  if (*p == '-') {
+    sign = -1;
+    p++;
+  }
+  while (*p >= '0' && *p <= '9') {
+    *d = *d * 10 + *p - '0';
+    p++;
+  }
+  *d *= sign;
+  *pp = p;
+}
+
+static void run(size_t i, std::vector<int>& codes) {
+  // printf("execute %d at %zu\n", codes[i], i);
+  switch (codes[i]) {
+  case 1:
+    codes[codes[i + 3]] = codes[codes[i + 1]] + codes[codes[i + 2]];
+    run(i + 4, codes);
+    break;
+  case 101:
+    codes[codes[i + 3]] = codes[i + 1] + codes[codes[i + 2]];
+    run(i + 4, codes);
+    break;
+  case 1001:
+    codes[codes[i + 3]] = codes[codes[i + 1]] + codes[i + 2];
+    run(i + 4, codes);
+    break;
+  case 1101:
+    codes[codes[i + 3]] = codes[i + 1] + codes[i + 2];
+    run(i + 4, codes);
+    break;
+  case 2:
+    codes[codes[i + 3]] = codes[codes[i + 1]] * codes[codes[i + 2]];
+    run(i + 4, codes);
+    break;
+  case 102:
+    codes[codes[i + 3]] = codes[i + 1] * codes[codes[i + 2]];
+    run(i + 4, codes);
+    break;
+  case 1002:
+    codes[codes[i + 3]] = codes[codes[i + 1]] * codes[i + 2];
+    run(i + 4, codes);
+    break;
+  case 1102:
+    codes[codes[i + 3]] = codes[i + 1] * codes[i + 2];
+    run(i + 4, codes);
+    break;
+  case 3:
+    codes[codes[i + 1]] = input;
+    run(i + 2, codes);
+    break;
+  case 4:
+    // printf("%d\n", codes[codes[i + 1]]);
+    outputs.push_back(codes[codes[i + 1]]);
+    run(i + 2, codes);
+    break;
+  case 104:
+    // printf("%d\n", codes[i + 1]);
+    outputs.push_back(codes[i + 1]);
+    run(i + 2, codes);
+    break;
+  case 99:
+    break;
+  default:
+    printf("UNKNOWN CODE %d at %zu\n", codes[i], i);
+    break;
+  }
 }
+
+int day5(line_view file) {
+  const char* p = file.line;
+  std::vector<int> optcodes;
+  while (p < file.line + file.length) {
+    if ((*p >= '0' && *p <= '9') || *p == '-') {
+      int d{0};
+      get_number(&p, &d);
+      optcodes.push_back(d);
+    }
+    p++;
+  }
+  input = 1;
+  run(0, optcodes);
+  return outputs[outputs.size() - 1];
+}
+
+} // namespace aoc2019