Day 12 Python solutions

Author: creideiki

12-1.py

@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+
+import heapq
+import numpy
+
+class Map:
+    def __init__(self, input):
+        self.height = len(input)
+        self.width = len(input[0])
+        self.map = numpy.zeros((self.height, self.width), dtype=numpy.uint)
+
+        for row in range(self.height):
+            for col in range(self.width):
+                if input[row][col] == "S":
+                    self.start = [row, col]
+                    self.map[row, col] = 0
+                elif input[row][col] == "E":
+                    self.end = [row, col]
+                    self.map[row, col] = ord('z') - ord('a')
+                else:
+                    self.map[row, col] = ord(input[row][col]) - ord('a')
+
+        self.lengths = numpy.empty((self.height, self.width), dtype=numpy.uint)
+        self.lengths.fill(pow(2, 32) - 1)
+        self.lengths[self.start[0], self.start[1]] = 0
+
+    def solve(self):
+        queue = []
+        heapq.heappush(queue, (0, (self.start[0], self.start[1])))
+
+        while len(queue) > 0:
+            length, coords = heapq.heappop(queue)
+            row, col = coords
+            if length > self.lengths[row, col]:
+                continue
+
+            ns = [
+                [row + 1, col],
+                [row - 1, col],
+                [row, col + 1],
+                [row, col - 1]
+            ]
+
+            neighbours = []
+            for n in ns:
+                if n[0] >= 0 and \
+                   n[0] < self.height and \
+                   n[1] >= 0 and \
+                   n[1] < self.width and \
+                   self.map[n[0], n[1]] <= self.map[row, col] + 1:
+                    neighbours.append((n[0], n[1]))
+
+            for v in neighbours:
+                new_length = length + 1
+                if new_length < self.lengths[v[0], v[1]]:
+                    self.lengths[v[0], v[1]] = new_length
+                    heapq.heappush(queue, (new_length, (v[0], v[1])))
+
+        return self.lengths[self.end[0], self.end[1]]
+
+
+lines = [list(line.strip()) for line in open('12.input').readlines()]
+
+map = Map(lines)
+
+print(map.solve())

12-2.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python
+
+import heapq
+import numpy
+
+class Map:
+    def __init__(self, input):
+        self.height = len(input)
+        self.width = len(input[0])
+        self.map = numpy.zeros((self.height, self.width), dtype=numpy.uint)
+
+        for row in range(self.height):
+            for col in range(self.width):
+                if input[row][col] == "S":
+                    self.map[row, col] = 0
+                elif input[row][col] == "E":
+                    self.start = [row, col]
+                    self.map[row, col] = ord('z') - ord('a')
+                else:
+                    self.map[row, col] = ord(input[row][col]) - ord('a')
+
+        self.lengths = numpy.empty((self.height, self.width), dtype=numpy.uint)
+        self.lengths.fill(pow(2, 32) - 1)
+        self.lengths[self.start[0], self.start[1]] = 0
+
+    def solve(self):
+        queue = []
+        heapq.heappush(queue, (0, (self.start[0], self.start[1])))
+
+        while len(queue) > 0:
+            length, coords = heapq.heappop(queue)
+            row, col = coords
+            if length > self.lengths[row, col]:
+                continue
+
+            ns = [
+                [row + 1, col],
+                [row - 1, col],
+                [row, col + 1],
+                [row, col - 1]
+            ]
+
+            neighbours = []
+            for n in ns:
+                if n[0] >= 0 and \
+                   n[0] < self.height and \
+                   n[1] >= 0 and \
+                   n[1] < self.width and \
+                   self.map[row, col] <= self.map[n[0], n[1]] + 1:
+                    neighbours.append((n[0], n[1]))
+
+            for v in neighbours:
+                new_length = length + 1
+                if new_length < self.lengths[v[0], v[1]]:
+                    self.lengths[v[0], v[1]] = new_length
+                    heapq.heappush(queue, (new_length, (v[0], v[1])))
+
+    def solution(self):
+        closest = pow(2, 32) - 1
+
+        it = numpy.nditer(self.map, flags=['multi_index'])
+        for element in it:
+            if element > 0:
+                continue
+
+            if self.lengths[it.multi_index[0], it.multi_index[1]] < closest:
+                closest = self.lengths[it.multi_index[0], it.multi_index[1]]
+
+        return closest
+
+
+lines = [list(line.strip()) for line in open('12.input').readlines()]
+
+map = Map(lines)
+
+map.solve()
+
+print(map.solution())