rename stuff

2021/day21/AoC21.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+
+import sys, re
+
+def memo(fc):
+    memo = {}
+    def f2(a,b,c,d,e,f,g):
+        if (a,b,c,d,e,f,g) not in memo: memo[(a,b,c,d,e,f,g)] = fc(a,b,c,d,e,f,g)
+        return memo[(a,b,c,d,e,f,g)]
+    return f2
+
+def parse(line):
+    groups = re.compile(r"Player 1 starting position: (?P<p1>\d+)\nPlayer 2 starting position: (?P<p2>\d+)").search(line)
+    return groups
+
+def step(p1,p2):
+    d,s1,s2,die,dr = 0,0,0,0,0
+    t = 1
+    while s1 < 1000 and s2 < 1000:
+        mv = d*3 + 6
+        d = d + 3 % 100
+        dr += 3
+        if t == 1:
+            p1 = (p1 + mv - 1) % 10 + 1
+            s1 += p1
+        if t == 2:
+            p2 = (p2 + mv - 1) % 10 + 1
+            s2 += p2
+        t = t%2+1
+    return dr*s2 if s2 < 1000 else dr*s1
+
+@memo
+def qstep(p1,p2,s1,s2,dv,t,dt):
+    if s1 >= 21:
+        return {1:1,2:0}
+    elif s2 >= 21:
+        return {1:0,2:1}
+    wins = {1: 0, 2: 0}
+    if t == 1:
+        if dt == 3:
+            nt = t%2+1
+            np1 = (p1 + dv - 1) % 10 + 1
+            ns1 = s1+np1
+            win = qstep(np1,p2,ns1,s2,0,nt,0)
+            wins[1] += win[1]
+            wins[2] += win[2]
+        else:
+            dt += 1
+            for d in range(1,4):
+                ndv = dv+d
+                win = qstep(p1,p2,s1,s2,ndv,t,dt)
+                wins[1] += win[1]
+                wins[2] += win[2]
+    if t == 2:
+        if dt == 3:
+            nt = t%2+1
+            np2 = (p2 + dv - 1) % 10 + 1
+            ns2 = s2+np2
+            win = qstep(p1,np2,s1,ns2,0,nt,0)
+            wins[1] += win[1]
+            wins[2] += win[2]
+        else:
+            dt += 1
+            for d in range(1,4):
+                ndv = dv+d
+                win = qstep(p1,p2,s1,s2,ndv,t,dt)
+                wins[1] += win[1]
+                wins[2] += win[2]
+    return wins
+
+if __name__ == '__main__':
+    p1,p2 = map(int,parse(open(sys.argv[1]).read()).groups())
+
+    # challenge 1
+    res1 = str(step(p1,p2))
+    print("challenge 1:" + "\n" +  res1 + "\n")
+
+    # challenge 2
+    results = qstep(p1,p2,0,0,0,1,0)
+
+    res2 = str(max(results.values()))
+    print("challenge 2:" + "\n" +  res2 + "\n")
+