# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh@octave.org>
# Date 1513700260 18000
# Node ID 836d284fff87e444466385bdfa6118fadbb22644
# Parent  776d882c78b8b7065159fa97e09cb16f52aac435
day 19

diff --git a/2017/day19.d b/2017/day19.d
new file mode 100644
--- /dev/null
+++ b/2017/day19.d
@@ -0,0 +1,66 @@
+import std.stdio;
+import std.array: array;
+import std.algorithm: map;
+import std.string: indexOf;
+import std.typecons: tuple;
+
+auto walkPath(T)(T grid) {
+  char[] path;
+  long i = grid[0].indexOf("|"), j = 1;
+  int steps = 1;
+  enum DIR {u, d, l, r};
+  DIR dir = DIR.d;
+  while(i > 0) {
+    steps++;
+    auto next = grid[j][i];
+
+    switch(next) {
+    case 'A': .. case 'Z':
+      path ~= next;
+      break;
+    case '+':
+      if(dir == DIR.u || dir == DIR.d) {
+        if(grid[j][i-1] == '-') {
+          dir = DIR.l;
+        }
+        else {
+          dir = DIR.r;
+        }
+      }
+      else {
+        if(grid[j-1][i] == '|') {
+          dir = DIR.u;
+        }
+        else {
+          dir = DIR.d;
+        }
+      }
+      break;
+    default:
+    }
+
+    final switch(dir){
+    case DIR.d:
+      j++;
+      break;
+    case DIR.u:
+      j--;
+      break;
+    case DIR.l:
+      i--;
+      break;
+    case DIR.r:
+      i++;
+      break;
+    }
+
+  }
+  return tuple(path, steps);
+}
+
+void main(string[] args) {
+  auto grid = File(args[1]).byLineCopy.array.dup;
+  auto ret = grid.walkPath;
+  writeln(ret[0]);
+  writeln(ret[1]);
+}