Add alternative solution for day 9

AoC2021/code/AoC09B.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+import sys
+from operator import mul
+from functools import reduce
+
+def adj(mp, x, y):
+    adj = {}
+    if x-1 > -1: adj[(-1,0)] = mp[x-1][y]
+    if x+1 < len(mp): adj[(1,0)] = mp[x+1][y]
+    if y-1 > -1: adj[(0,-1)] = mp[x][y-1]
+    if y+1 < len(mp[0]): adj[(0,1)] = mp[x][y+1]
+    return adj
+
+def risk(mp, x, y):
+    ad = adj(mp, x, y).values()
+    if all(map(lambda i: i > mp[x][y], ad)):
+        bas[(x,y)] = 0
+        return mp[x][y] + 1
+    else: return 0
+
+def basin(mp, x, y):
+    nex = min(adj(mp, x, y).items(), key=lambda i: i[1])
+    if (x,y) in bas: (i,j) = (x,y)
+    elif (x,y) in mem: (i,j) = mem[(x,y)]
+    else: 
+        (i,j) = basin(mp, x+nex[0][0], y+nex[0][1])
+        return (i,j)
+    bas[(i,j)] += 1
+    return (i,j)
+
+if __name__ == '__main__':
+    m = [[int(i) for i in l] for l in open(sys.argv[1]).read().strip('\n\n').split('\n')]
+
+    bas,mem = {},{}
+    # challenge 1
+    res1 = str(sum([sum([risk(m, x, y) for y in range(len(m[0]))]) for x in range(len(m))]))
+    print("challenge 1:" +"\n" +  res1 + "\n")
+
+    # challenge 2
+    ([([basin(m, x, y) for y in range(len(m[0])) if m[x][y] < 9]) for x in range(len(m))])
+    res2 = str(reduce(mul, sorted(bas.values(), reverse=True)[0:3]))
+    print("challenge 2:" +"\n" +  res2 + "\n")
+