2024 - Day 6 part 2 - bad, takes way too much time

2024/6/6_2_bad.py

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+#!/usr/bin/env python
+# 2024 - Advent Of Code 6 - part 2
+
+# file = 'input_example.txt'
+file = 'input.txt'
+
+input_lines = []
+with open(file, encoding="utf-8") as f:
+    for l in f.readlines():
+        input_lines.append(list(l.strip()))
+
+MAX_X = len(input_lines[0])
+MAX_Y = len(input_lines)
+
+vector=(0, 0)
+gx = 0
+gy = 0
+for y in range(0, MAX_Y):
+    for x in range(0, MAX_X):
+        g = input_lines[y][x]
+        if g not in ('.', '#'):
+            gx = x
+            gy = y
+            print(f'found guard at {x}, {y}')
+            if g == '^':
+                vector = (0, -1)
+            if g == 'v':
+                vector = (0, 1)
+            if g == '>':
+                vector = (1, 0)
+            if g == '<':
+                vector = (-1, 0)
+            print(f'{vector=}')
+
+moves = [(0,-1), (1, 0), (0, 1), (-1, 0)]
+move = moves.index(vector)
+
+def move_and_detect(grid, posx, posy, v, m):
+    visited = [(posx, posy, v)]
+    while 0 < posx < MAX_X and 0 < posy < MAX_Y:
+        nx = posx + v[0]
+        ny = posy + v[1]
+        if nx < 0 or nx >= MAX_X or ny < 0 or ny >= MAX_Y:
+            return False
+        if grid[ny][nx] != '#':
+            posx += v[0]
+            posy += v[1]
+            if (posx, posy, v) in visited:
+                return True
+            visited.append((posx, posy, v))
+        else:
+            m += 1
+            v = moves[m % 4]
+
+    return False
+
+start_gx = gx
+start_gy = gy
+start_vector = vector
+start_move = move
+found_loop = set()
+while 0 <= gx < MAX_X and 0 <= gy < MAX_Y:
+    nextx = gx + vector[0]
+    nexty = gy + vector[1]
+    if nextx < 0 or nextx >= MAX_X or nexty < 0 or nexty >= MAX_Y:
+        break
+    if input_lines[nexty][nextx] != '#':
+        # print(f'testing bloc at {nextx}, {nexty}')
+        old_value = input_lines[nexty][nextx]
+        input_lines[nexty][nextx] = '#'
+        if (nextx, nexty) not in found_loop:
+            if move_and_detect(input_lines, start_gx, start_gy, start_vector, start_move):
+                print(f'found loop with bloc at {nextx}, {nexty}')
+                found_loop.add((nextx, nexty))
+        input_lines[nexty][nextx] = old_value
+        gx = nextx
+        gy = nexty
+    else:
+        move += 1
+        vector = moves[move % 4]
+        # print(f'new vector: {vector}')
+
+print(f'{len(found_loop)=}')