2016 day1 move

1 files changed, 59 insertions, 1 deletions

diff --git a/src/2016/day1/aoc.h b/src/2016/day1/aoc.h
index 95823fe..66e97d1 100644
--- a/src/2016/day1/aoc.h
+++ b/src/2016/day1/aoc.h
@@ -1,6 +1,64 @@
 #pragma once
 #include "common.h"
+#include <algorithm>
+#include <math.h>
+#include <vector>
 
 namespace aoc2016 {
 
-}
+struct instruction {
+  enum {
+    left = 0,
+    right,
+  } direction;
+  int distance;
+};
+
+struct position {
+  enum bearing {
+    north = 0,
+    east,
+    south,
+    west,
+  } b;
+
+  int x;
+  int y;
+
+  int blocks(position p) const noexcept { return abs(p.x - x) + abs(p.y - y); }
+
+  position move(instruction i) const noexcept {
+    auto putx = [this](int d) { return x; };
+    auto puty = [this](int d) { return y; };
+    auto addx = [this](int d) { return x + d; };
+    auto subx = [this](int d) { return x - d; };
+    auto addy = [this](int d) { return y + d; };
+    auto suby = [this](int d) { return y - d; };
+
+    struct {
+      bearing bs[2];
+      std::function<int(int)> lr[4];
+    } moves[] = {
+        {{west, east}, {subx, addx, puty, puty}},
+        {{north, south}, {putx, putx, addy, suby}},
+        {{east, west}, {addx, subx, puty, puty}},
+        {{south, north}, {putx, putx, suby, addy}},
+    };
+    position next;
+    next.b = moves[int(b)].bs[int(i.direction)];
+    next.x = moves[int(b)].lr[int(i.direction)](i.distance);
+    next.y = moves[int(b)].lr[int(i.direction) + 2](i.distance);
+
+    return next;
+  }
+
+  position move(const std::vector<instruction>& is) const noexcept {
+    position next;
+    std::for_each(is.begin(), is.end(), [&next, this](const instruction& i) { next = move(i); });
+    return next;
+  }
+};
+
+std::vector<instruction> parse_day1(line_view);
+
+} // namespace aoc2016