day 3

3/3.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+
+import sys
+
+cgrid = {}
+grids = []
+
+for line in sys.stdin:
+  grid = {}
+
+  instructions = line.rstrip().split(',')
+  pos_x = 0
+  pos_y = 0
+  steps = 0
+      
+  for i in instructions:
+    dir = i[0]
+    num = int(i[1:])
+    for j in range(0,num):
+      steps += 1
+      if dir == 'U':
+        pos_y += 1
+      elif dir == 'D':
+        pos_y -= 1
+      elif dir == 'L':
+        pos_x -= 1
+      elif dir == 'R':
+        pos_x += 1
+      s = "%d,%d" % (pos_x, pos_y)
+      if s not in grid:
+        grid[s] = steps
+    #print (dir, num, "grid:", pos_x, pos_y)
+
+  grids.append(grid)
+  # curses, it's possible for a wire to cross itself. Dirty bodge. 
+  for pos, c in grid.items():
+    if pos in cgrid:
+      cgrid[pos] += 1
+    else:
+      cgrid[pos] = 1
+
+least = None
+leastSteps = None
+for pos, c in cgrid.items():
+  if c > 1: 
+    coords = pos.split(',')
+    dist = abs( int(coords[0]) ) + abs( int(coords[1]) )
+    allsteps = grids[0][pos] + grids[1][pos]
+
+    if least is None or dist < least:
+      least = dist
+    if leastSteps is None or allsteps < leastSteps:
+      leastSteps = allsteps
+    #print(c, coords, dist, least, leastSteps)
+
+print(least, leastSteps)