Add solution for day 15 (inefficient)

AoC2021/code/AoC15.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+
+import sys
+
+def memo(f):
+    memo = {}
+
+    def f2(a,x,y,c,e):
+        if (x,y) not in memo: memo[(x,y)] = f(a,x,y,c,e)
+        return memo[(x,y)]
+    return f2
+
+def nb(sx, sy):
+    n = [(0,1), (1,0), (0,-1), (-1,0)]
+    return [(max(0,sx+x), max(0,sy+y)) for x,y in n]
+
+def dijkstra(graph, s):
+    a = {}
+    v = {}
+    Q = initG(graph, s, a, v)
+    lq = len(Q)
+    while len(Q) > 0:
+        u = min([u for u in Q], key=lambda x: a[x])
+        Q.remove(u)
+        for vo in nb(*u):
+            if vo in Q:
+                distance_update(graph, u,vo,a,v)
+        if (len(Q)/lq * 100 % 1) == 0:
+            print("|", end='', flush=True)
+    print("\n")
+    return v
+
+def initG(graph, s, a, v):
+    for vo in graph.keys():
+        a[vo] = 9999999999999999
+        v[vo] = 'null'
+    a[s] = 0
+    Q = [n for n in graph.keys()]
+    return Q
+
+def distance_update(g, u,vo,a,v):
+    alt = a[u] + g[u]
+    if alt < a[vo]:
+        a[vo] = alt
+        v[vo] = u
+
+def shortest_path(g, d, v):
+    w = [d]
+    u = d
+    r = 0
+    while v[u] != 'null':
+        r += g[u]
+        u = v[u]
+        w.append(u)
+    return w.reverse(), r
+
+if __name__ == '__main__':
+    nums = [[int(i) for i in list(line.strip('\n'))] for line in open(sys.argv[1])]
+    
+    # challenge 1
+    g1 = {(x,y) : nums[y][x] for x in range(len(nums[0])) for y in range(len(nums))}
+    v = dijkstra(g1, (0,0))
+    w, r = shortest_path(g1, (len(nums)-1, len(nums[0])-1), v)
+
+    res1 = str(r)
+    print("challenge 1:" +"\n" +  res1 + "\n")
+
+    # challenge 2 - inefficient
+    g2 = {(x+i*len(nums[0]),y+j*len(nums)) : (nums[y][x] + i + j if nums[y][x] + i + j < 10 else (nums[y][x] + i + j) % 10 + 1)  for x in range(len(nums[0])) for y in range(len(nums)) for i in range(5) for j in range(5)}
+    v = dijkstra(g2, (0,0))
+    w, r = shortest_path(g2, (len(nums[0])*5-1, len(nums)*5-1), v)
+
+    res2 = str(r)
+    print("challenge 2:" +"\n" +  res2 + "\n")
+