Finished 2017/18

2017/19/19.md

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+## \-\-- Day 19: A Series of Tubes \-\--
+
+Somehow, a network packet got
+lost
+and ended up here. It\'s trying to follow a routing diagram (your puzzle
+input), but it\'s confused about where to go.
+
+Its starting point is just off the top of the diagram. Lines (drawn with
+`|`, `-`, and `+`) show the path it needs to take, starting by going
+down onto the only line connected to the top of the diagram. It needs to
+follow this path until it reaches the end (located somewhere within the
+diagram) and stop there.
+
+Sometimes, the lines cross over each other; in these cases, it needs to
+continue going the same direction, and only turn left or right when
+there\'s no other option. In addition, someone has left *letters* on the
+line; these also don\'t change its direction, but it can use them to
+keep track of where it\'s been. For example:
+
+         |          
+         |  +--+    
+         A  |  C    
+     F---|----E|--+ 
+         |  |  |  D 
+         +B-+  +--+ 
+
+Given this diagram, the packet needs to take the following path:
+
+-   Starting at the only line touching the top of the diagram, it must
+    go down, pass through `A`, and continue onward to the first `+`.
+-   Travel right, up, and right, passing through `B` in the process.
+-   Continue down (collecting `C`), right, and up (collecting `D`).
+-   Finally, go all the way left through `E` and stopping at `F`.
+
+Following the path to the end, the letters it sees on its path are
+`ABCDEF`.
+
+The little packet looks up at you, hoping you can help it find the way.
+*What letters will it see* (in the order it would see them) if it
+follows the path? (The routing diagram is very wide; make sure you view
+it without line wrapping.)
+
+To begin, [get your puzzle input](19/input).
+
+Answer:

2017/19/solution.py

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+#!/bin/python3
+import sys,re
+from pprint import pprint
+sys.path.insert(0, '../../')
+from fred import list2int
+
+input_f = 'test'
+
+part = 1
+#########################################
+#                                       #
+#              Part 1                   #
+#                                       #
+#########################################
+
+grid = []
+
+start = ()
+prev = ()
+
+def valid_n(grid,cur):
+    r,c = cur
+    count = 0
+    if grid[r-1][c] != ' ':
+        count += 1
+    if grid[r+1][c] != ' ':
+        count += 1
+    if grid[r][c+1] != ' ':
+        count += 1
+    if grid[r][c-1] != ' ':
+        count += 1
+    return count
+
+
+if part == 1:
+    with open(input_f) as file:
+        for line in file:
+            grid.append(list(line.rstrip()))
+
+    for r, row in enumerate(grid):
+        for c, col in enumerate(row):
+            print(grid[r][c],end='')
+        print()
+            
+    for r, row in enumerate(grid):
+        for c, col in enumerate(row):
+            if r == 0:
+                if grid[r][c] == '|':
+                    start = (r,c)
+
+    end = False
+    cur = start
+    prev = (-1,-1)
+    prev_dir = {
+        'up': False,
+        'down': False,
+        'left': False,
+        'right': False
+    }
+
+    while not end:
+        r,c = cur
+        try:
+            if grid[r-1][c] != ' ' and prev != (r-1,c):
+                print('up',grid[r-1][c])
+                
+                prev = cur
+                prev_dir = {
+                    'up': True,
+                    'down': False,
+                    'left': False,
+                    'right': False
+                }
+                cur = (r-1,c)
+        except Exception as e:
+            print(e)
+        
+        try:
+            if grid[r+1][c] != ' ' and prev != (r+1,c):
+                print('down',grid[r+1][c])
+                if valid_n(grid,cur) >= 1 and prev_dir['down']:
+                    prev = cur
+                    prev_dir = {
+                        'up': False,
+                        'down': True,
+                        'left': False,
+                        'right': False
+                    }
+                    cur = (r+1,c)
+        except Exception as e:
+            print(e)
+        
+        try:
+            if grid[r][c-1] != ' ' and prev != (r,c-1) and not prev_dir['left']:
+                print('left',grid[r][c-1])
+                prev = cur
+                prev_dir = {
+                    'up': False,
+                    'down': False,
+                    'left': True,
+                    'right': False
+                }
+                cur = (r,c-1)
+        except Exception as e:
+            print(e)
+        
+        try:
+            if grid[r][c+1] != ' ' and prev != (r,c+1) and not prev_dir['right']:
+                print('right',grid[r][c+1])
+                prev = cur
+                prev_dir = {
+                    'up': False,
+                    'down': False,
+                    'left': False,
+                    'right': True
+                }
+                cur = (r,c+1)
+        except Exception as e:
+            print(e)
+        input()
+    
+
+
+#########################################
+#                                       #
+#              Part 2                   #
+#                                       #
+#########################################
+if part == 2:
+    exit()