Add day 9 solution

day-09/day-09.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+from pathlib import Path
+
+
+def part_1(input):
+    result = 0
+    m = [[int(d) for d in l.rstrip()] for l in input]
+    for y, l in enumerate(m):
+        for x, d in enumerate(l):
+            lowest = True
+            if 0 < y and d >= m[y-1][x]:
+                lowest = False
+            elif (len(m) - 1) > y and d >= m[y+1][x]:
+                lowest = False
+            elif 0 < x and d >= m[y][x-1]:
+                lowest = False
+            elif (len(l) - 1) > x and d >= m[y][x+1]:
+                lowest = False
+            if lowest:
+                result += d + 1
+
+    print("Part 1 result:", result)
+
+
+def part_2(input):
+    result = 0
+    m = [[int(d) for d in l.rstrip()] for l in input]
+    p_lowest = set()
+    p_low = set()
+    for y, l in enumerate(m):
+        for x, d in enumerate(l):
+            low = True
+            if d != 9:
+                p_low.add((x, y))
+            if 0 < y and d >= m[y-1][x]:
+                low = False
+            elif (len(m) - 1) > y and d >= m[y+1][x]:
+                low = False
+            elif 0 < x and d >= m[y][x-1]:
+                low = False
+            elif (len(l) - 1) > x and d >= m[y][x+1]:
+                low = False
+            if low:
+                p_lowest.add((x, y))
+    b_size = []
+    neighbors = [[-1, 0], [0, -1], [0, 1], [1, 0]]
+    for k in p_lowest:
+        to_check = [k]
+        basin = set()
+        while len(to_check):
+            p = to_check.pop(0)
+            basin.add(p)
+            for n in neighbors:
+                tup = (p[0] + n[0], p[1] + n[1])
+                if tup in p_low and tup not in basin and tup not in to_check:
+                    to_check.append(tup)
+        b_size.append(len(basin))
+
+    b_size.sort()
+    result = b_size[-3] * b_size[-2] * b_size[-1]
+    print("Part 2 result:", result)
+
+
+input = list()
+p = Path(__file__).with_name('input.txt')
+with open(p) as f:
+    input = f.readlines()
+    part_1(input)
+    part_2(input)