Extend lib and solve day 17 with A*. Fun.

lib.py

@@ -1,4 +1,134 @@
 import re
+import os
+import string
+import heapq
+
+NUMBERS = string.digits
+LETTERS_LOWER = string.ascii_lowercase
+LETTERS_UPPER = string.ascii_uppercase
+
+UP = (-1, 0)
+DOWN = (1, 0)
+RIGHT = (0, 1)
+LEFT = (0, -1)
+
+NORTH = UP
+SOUTH = DOWN
+EAST = RIGHT
+WEST = LEFT
+
+INF = float("inf")
+fst = lambda l: l[0]
+snd = lambda l: l[1]
+
+def maps(f, xs):
+    if isinstance(xs, list):
+        return [maps(f, x) for x in xs]
+    return f(xs)
+
+def mape(f, xs):
+    return list(map(f, xs))
+
+def add2(a: tuple[int, int], b: tuple[int, int]) -> tuple[int, int]:
+    return (a[0] + b[0], a[1] + b[1])
+
+class Grid2D:
+    def __init__(self, text: str):
+        lines = [line for line in text.splitlines() if line.strip() != ""]
+        self.grid = list(map(list, lines))
+        self.n_rows = len(self.grid)
+        self.n_cols = len(self.grid[0])
+
+    def __getitem__(self, pos: tuple[int, int]):
+        row, col = pos
+        return self.grid[row][col]
+
+    def __setitem__(self, pos: tuple[int, int], val):
+        row, col = pos
+        self.grid[row][col] = val
+
+    def clone_with_val(self, val):
+        c = Grid2D("d\nd")
+        c.n_rows = self.n_rows
+        c.n_cols = self.n_cols
+        c.grid = [[val for _ in range(c.n_cols)]
+                  for _ in range(self.n_rows)]
+        return c
+
+    def rows(self) -> list[list[str]]:
+        return [row for row in self.grid]
+
+    def cols(self) -> list[list[str]]:
+        rows = self.rows()
+        return [[row[col_i] for row in rows]
+                for col_i in range(self.n_cols)]
+
+    def find(self, chars: str) -> list[tuple[int, int]]:
+        r = []
+        for row_i in range(self.n_rows):
+            for col_i in range(self.n_cols):
+                c = (row_i, col_i)
+                if self[c] in chars:
+                    r.append(c)
+        return r
+
+    def all_coords(self) -> list[tuple[int, int]]:
+        return [(row_i, col_i)
+                for row_i in range(self.n_rows)
+                for col_i in range(self.n_cols)]
+
+    def row_coords(self, row_i) -> list[tuple[int, int]]:
+        assert row_i < self.n_rows, f"{row_i=} must be smaller than {self.n_rows=}"
+        return [(col_i, row_i) for col_i in range(self.n_cols)]
+
+    def col_coords(self, col_i) -> list[tuple[int, int]]:
+        assert col_i < self.n_cols, f"{col_i=} must be smaller than {self.n_cols=}"
+        return [(col_i, row_i) for row_i in range(self.n_rows)]
+
+    def contains(self, pos: tuple[int, int]) -> bool:
+        row, col = pos
+        return row >= 0 and row < self.n_rows and col >= 0 and col < self.n_cols
+
+    def neighbors_ort(self, pos: tuple[int, int]) -> list[tuple[int, int]]:
+        ort_rel = [(-1, 0), (0, 1), (1, 0), (0, -1)]
+        return [add2(pos, off) for off in ort_rel if self.contains(add2(pos, off))]
+
+    def neighbors_vert(self, pos: tuple[int, int]) -> list[tuple[int, int]]:
+        ort_vert = [(-1, -1), (-1, 1), (1, 1), (1, -1)]
+        return [add2(pos, off) for off in ort_vert if self.contains(add2(pos, off))]
+
+    def neighbors_adj(self, pos: tuple[int, int]) -> list[tuple[int, int]]:
+        return self.neighbors_ort(pos) + self.neighbors_vert(pos)
+
+    def print(self):
+        for r in self.rows():
+            print("".join(r))
+
+    def print_with_gaps(self):
+        for r in self.rows():
+            print(" ".join(map(str, r)))
+
+class Input:
+    def __init__(self, text: str):
+        if os.path.isfile(text):
+            self.text = open(text).read()
+        else:
+            self.text = text
+
+    def stats(self):
+        print(f" size: {len(self.text)}")
+        print(f"lines: {len(self.text.splitlines())}")
+        ps = len(self.paras())
+        print(f"paras: {ps}")
+
+    def lines(self) -> list[str]:
+        return self.text.splitlines()
+
+    def paras(self) -> list[list[str]]:
+        return [p.splitlines() for p in self.text.split("\n\n")]
+
+    def grid2(self) -> Grid2D:
+        return Grid2D(self.text)
 
 def prime_factors(n):
     """
@@ -32,14 +162,15 @@ def lcm(numbers: list[int]) -> int:
         s *= f
     return s
 
-def str_to_single_int(line: str) -> int:
+def str_to_int(line: str) -> int:
     line = line.replace(" ", "")
     r = re.compile(r"-?\d+")
-    for m in r.findall(line):
-        return int(m)
-    raise Exception("No single digit sequence in '{line}'")
+    m = r.findall(line)
+    assert len(m) == 0, "str_to_int no int"
+    assert len(m) > 1, "str_to_int multiple ints"
+    return int(m[0])
 
-def str_to_int_list(line: str) -> list[int]:
+def str_to_ints(line: str) -> list[int]:
     r = re.compile(r"-?\d+")
     return list(map(int, r.findall(line)))
 
@@ -48,3 +179,40 @@ def str_to_lines_no_empty(text: str) -> list[str]:
 
 def str_to_lines(text: str) -> list[str]:
     return list(text.splitlines())
+
+def count_trailing_repeats(lst):
+    count = 0
+    for elem in reversed(lst):
+        if elem != lst[-1]:
+            break
+        else:
+            count += 1
+    return count
+
+class A_Star(object):
+    def __init__(self, starts, is_goal, h, d, neighbors):
+        """
+        :param h: heuristic function
+        :param d: cost from node to node function
+        :param neighbors: neighbors function
+        """
+        open_set = []
+        g_score = {}
+
+        for start in starts:
+            heapq.heappush(open_set, (h(start), start))
+            g_score[start] = d(0, start)
+
+        while open_set:
+            current_f_score, current = heapq.heappop(open_set)
+            if is_goal(current):
+                self.cost = current_f_score
+                break
+
+            for neighbor in neighbors(current):
+                tentative_g_score = g_score[current] + d(current, neighbor)
+                if neighbor not in g_score or \
+                   tentative_g_score < g_score[neighbor]:
+                    g_score[neighbor] = tentative_g_score
+                    f_score = g_score[neighbor] + h(neighbor)
+                    heapq.heappush(open_set, (f_score, neighbor))