1 files changed, 41 insertions, 0 deletions
diff --git a/server/old/fast_P_nim.py b/server/old/fast_P_nim.py
new file mode 100644
index 0000000..adafca1
--- /dev/null
+++ b/server/old/fast_P_nim.py
@@ -0,0 +1,41 @@
+hashStuff = {0: 0, 1: 1, 2: 1, 3: 1, 4: 2, 5: 2}
+
+def MEX(S):
+    i = 0
+    while True:
+        if i not in S:
+            return i
+        i += 1
+
+def P(n):
+    if n in hashStuff:
+        return hashStuff[n]
+    res = Prec(n)
+    hashStuff[n] = res
+    return res
+
+def Prec(n):
+    S = set()
+    # Works only for n >= 5
+    S.add(P(n-2))
+    S.add(P(n-3))
+    S.add(P(n-4))
+    for i in range(2,n-5+1):
+        S.add(nimAdd(P(i),P(n-3-i)))
+    return MEX(S)
+
+def nimAdd(x, y):
+    return x ^ y
+
+# P(7)
+# for i in range(1,1000):
+#     print(f"Path, n={i} (oeis={i-1}): {P(i)}")
+
+# Pgames = set()
+# for i in range(20000):
+#     if hashStuff[i] == 0:
+#         Pgames.add(i)
+
+# for i in range(200):
+#     print(i, P(1000*i))
+