update

2025-10-18 13:38:38 +03:00
parent 9a38d895f0
commit 8369cddcd8
6 changed files with 602 additions and 0 deletions
@@ -0,0 +1,80 @@
+
+
+def f(inp):
+    def g(i, j, l):
+        old_i, old_j = i, j
+        visited.add((i, j))
+        if (i, j)==end:
+            paths.append(l)
+        else:
+            crossing = False
+            deadend = False
+            oi, oj = i, j
+            while not (crossing or deadend or (i, j)==end):
+                steps = []
+                for di, dj in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
+                    if inp[i+di][j+dj] in '.v>':
+                        steps.append((i+di, j+dj))
+                if len(steps)>2:
+                    crossing = True
+                    continue
+                if (oi, oj)!=steps[0]:
+                    oi, oj = i, j
+                    i, j = steps[0] 
+                elif len(steps)==2:
+                    oi, oj = i, j
+                    i, j = steps[1]
+                else:
+                    deadend = True
+                    continue
+                l += 1
+            if deadend:
+                return
+            elif (i, j)==end:
+                g(i, j, l)                
+            elif crossing and (i, j) not in visited:
+                for di, dj in [(0, 1), (1, 0), (0, -1), (-1, 0)]:
+                    if di==1 and inp[i+di][j+dj]=='v':
+                        g(i+di, j+dj, l+1)
+                    elif dj==1 and inp[i+di][j+dj]=='>':
+                        g(i+di, j+dj, l+1)
+        visited.remove((old_i, old_j))
+    visited = set()
+    paths = []
+    inp = ['#'*len(inp[0])] + inp + ['#'*len(inp[0])]
+    si = 1
+    sj = inp[1].index('.')
+    end = (len(inp)-2, inp[-2].index('.'))
+    g(si, sj, 0)
+    return sorted(paths, reverse=True)
+
+inp = '''
+#.#####################
+#.......#########...###
+#######.#########.#.###
+###.....#.>.>.###.#.###
+###v#####.#v#.###.#.###
+###.>...#.#.#.....#...#
+###v###.#.#.#########.#
+###...#.#.#.......#...#
+#####.#.#.#######.#.###
+#.....#.#.#.......#...#
+#.#####.#.#.#########v#
+#.#...#...#...###...>.#
+#.#.#v#######v###.###v#
+#...#.>.#...>.>.#.###.#
+#####v#.#.###v#.#.###.#
+#.....#...#...#.#.#...#
+#.#########.###.#.#.###
+#...###...#...#...#.###
+###.###.#.###v#####v###
+#...#...#.#.>.>.#.>.###
+#.###.###.#.###.#.#v###
+#.....###...###...#...#
+#####################.#
+'''.strip().split('\n')
+
+assert f(inp)==[94, 90, 86, 82, 82, 74]
+
+inp = open('input.txt').read().strip().split('\n')
+print(max(f(inp)))