Solve day 9 part 1

2022/09/a.py

@@ -1,18 +1,57 @@
 import os, argparse
+import numpy as np
+
+debug_print = print
+debug_print = lambda x: x
 
 def solve_task(lines):
     s = Snake()
+    s.print()
     for line in lines:
-        s.go(line)
+        s.do(line)
+        #s.print()
+    print(len(s.visited))
 
 class Snake:
     def __init__(self):
-        x = 0
-        y = 0
+        self.H = np.array([0, 0])
+        self.last_H = self.H
+        self.T = np.array([0, 0])
+        self.visited = set()
+        self.visited.add((0,0))
+
+    def print(self):
+        print(f"H: {self.H}, T: {self.T}")
+        print(self.visited)
     
-    def go(instruction):
+    def do(self, instruction):
         command = instruction.split(' ')[0]
         distance = int(instruction.split(' ')[1])
+        for _ in range(distance):
+            self.go(command)
+            self.adjust_tail()
+
+    def go(self, direction):
+        debug_print(f"Moving {direction}")
+        self.last_H = self.H.copy()
+        if direction == 'R':
+            self.H[0] += 1
+        elif direction == 'L':
+            self.H[0] -= 1
+        elif direction == 'U':
+            self.H[1] += 1
+        elif direction == 'D':
+            self.H[1] -= 1
+    
+    def adjust_tail(self):
+        debug_print(f"Euclidian distance from T:{self.T} to H:{self.H} is {np.linalg.norm(self.H - self.T)}")
+        if np.linalg.norm(self.H - self.T) >= 2:
+            debug_print(f"Tail moving from {self.T} to {self.last_H}")
+            self.T = self.last_H
+            self.visited.add(tuple(self.T))
+        else:
+            debug_print(f"Tail not moving from {self.T} to {self.last_H}")
+
 
 def read_lines(filename):
     lines = []