day 9 python part 2

day09/day09.py

@@ -31,6 +31,25 @@ def follow():
     y += sgn(H[1] - T[1])
     return x,y
 
+def follow2(h, t):
+    if h == t:
+        return t
+    if abs(h[0] - t[0]) <= 1 and abs(h[1] - t[1]) <= 1:
+        return t
+    if h[1] == t[1]:
+        x,y = t
+        x = h[0] - sgn(h[0] - t[0])
+        return x,y
+    if h[0] == t[0]:
+        x,y = t
+        y = h[1] -  sgn(h[1]-t[1])
+        return x,y
+    # diagonal
+    x,y = t
+    x += sgn(h[0] - t[0])
+    y += sgn(h[1] - t[1])
+    return x,y
+
 def sgn(x):
     if x==0: return 0
     if x > 0: return 1
@@ -44,7 +63,22 @@ for line in open("input"):
         H = go(H, dir)
         T = follow()
         visited.add(T)
-        print(H,T)
+        #print(H,T)
 print(len(visited))
         
 
+R = [(0,0)]*10
+visited = set([R[-1]])
+for line in open("input"):
+    dir, count = line.split()
+    count = int(count)
+    for _ in range(count):
+        R[0] = go(R[0], dir)
+        for i in range(1,len(R)):
+            t = follow2(R[i-1], R[i])
+            if t == R[i]:
+                break
+            R[i] = t
+        visited.add(R[-1])
+        print(R)
+print(len(visited))